UPSC ONLINE ACADEMY

Raashid Shah

TIME & WORK SET 6

Q.1 A can do a piece of work in 5 days & B in 6 days & C in 12 days, then how long will they take all together ?A) 2 2/9B) 1 1/9C) 3 3/9D) 4 4/9Ans. AShortcut:(A+B+C) = xyz / xy + yz + zx5 * 6 * 12 / 5*6 + 6*12 + 12*5= 360 / 30+72+60=2 2/9 Q.2 5 men can prepare 10 toys in 6 days working 6 hrs. Then in how many days can 12 men prepare 16 toys working 8 hrs a day ?A) 3 daysB) 4 daysC) 5 daysD) 6 daysAns. AShortcut:M1D1W2T1 = M2D2T2W15*6*16*6 = 12 * D2*8*10D2=5*6*16*6 / 12*10*8= 3 days Q.3 15 Men do ½ work in 20 days. In how many days will 20 men do the full work ? A) 15 days B) 40 days C) 30 days D) 20 days Ans. C Since, men & days are inversely proportional while work & days are directly proportional i.e. 20 : 15 ? 20 : X½ : 1 X = 15 * 1 * 20 / 20 * ½ = 30 days Q.4 If 4 men or 7 women can finish a work in 60 days, in How many days same work can be finished by 8 men & 7 women ?A) 18 daysB) 19 daysC) 20 daysD) 21 daysAns. C1/ 8/4*60 + 7/7*60= 1/8/240 + 7/420On solving= 20 Q.5 A Contractor undertook to do work in 60 days. He employed 50 men. After 40 days he found that only half of the work had been done. How many additional men he should employ so that the work may be done in time ?A) 50B) 45C) 40D) 35Ans. A60 days – 40 days=20 daysRemaining work = 1-1/2 = ½In 40 days, ½ work is done by the 50 menTherefore, 50 * 40In 20 days, 50*40/20 = 100No. of additional men = 100-50 = 50    

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TIME & WORK SET 5

Q.1 A certain no. of men complete a work in 60 days. If there were 8 men more work could be finished in 10 days less. How many men were originally there ?A) 40B) 41C) 42D) 43Ans. AShortcut:No. of more men * (60-10) / 108*50/10=40 Q.2 A can do work in 7 days. If A does twice as much work as B in a given time, find how long A & B would take to do the work ?A) 4 2/4 daysB) 5 2/3 daysC) 4 2/3 daysD) 5 2/4 daysAns. CShortcut:A+B=xy/x+yi.e. 7*14/14+7= 4 2/3 days Q.3 10 men can finish a work in 10 days where it takes 12 women to finish it in 10 days. If 15 men & 6 women undertake to complete the work how many days will they take to complete it ?A) 5 daysB) 6 daysC) 7 daysD) 8 daysAns. A15 men=10*10/15=20/3 days6 women=12*10/6=20 days15men+6women=20/3 * 20 / 20/3+20 (we have used this formula: x*y/x+y)20*20/80=5 days Q.4 A,B & C can finish a work in 10,12 & 15 days. If B stops after 2 days how long would it take to A & C to finish the remaining work ?A) ½ workB) 1/3 workC) ¼ workD) 1/5 workAns. AShortcut:2 (1/10 + 1/15 + 1/12)Or 2*1/4=1/2 work Q.5 A is twice as good as workman as B. Together they finish in 14 days. In how many days can it be done by each separately ?A) 21 daysB) 22 daysC) 23 daysD) 24 daysAns. AShortcut:(Twice + one) = Thrice in 14 daysi.e. 14 * 3 = 42 daysor twice person = 42 / 2 = 21 days    

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TIME & WORK SET 4

Q.1 Two workers A & B working together completed a job in 5 days. If A worked twice as efficiently as he actually did & B worked 1/3 as efficiently as he actually did, the work would have been completed in 3 days. To complete the job alone, A would require ? A) 7 ½ days B) 6 ¼ days C) 8 ¾ days D) 5 1/5 days Ans. B Let A & B completes the job in x & y daysThus, 1/x + 1/y = 1/5–iAfter changing efficiencies A would be able to complete the work in x/2 days & B in 3x daysTherefore, 2/x + 1/3y = 1/3—iiOn solving these two equations we will getX = 6 ¼ days Q.2 A & B can complete a job in 24 days. A alone can complete in 32 days. Both of them worked together for 8 days & then A left. The number of days B will take to complete the remaining job is : A) 32 days B) 128 days C) 64 days D) 16 days Ans. C 1/A + 1/B = 1/24 & 1/A = 1/321/B = 1/24-1/32= 1/96B = 96 daysNow, 8/32 +8+x / 96 = 1Or 24+8+x=96X=96-32= 64 Shortcut:vabi.e. v 16 * 9 = 12 days Q.3 Ashok started a business with an investment of Rs. 10000. After a few months Alok joined him with an investment of Rs. 12000. At the end of one year from the start they shared Alok total profit equally. After how long did join ?A) 2 monthsB) 3 monthsC) 4 monthsD) 5 monthsAns. A10000 * 12 / 12000 * x = 1:110 / x = 1:1X=10Therefore , he joined the business with Ashok after 2 months Q.4 X & Y started a business with an investment of Rs.20000 & Rs.24000. At the end of one year total profit they shared was Rs.1000 more than the difference in their profit shares. Find the total profit ?A) 1100B) 1200C) 1300D) 1400Ans. A20000 : 24000 = 5 : 6Let the total profit share be 5x & 6x5x + 6x = 6x – 5x + 1000Therefore, 11x = x+1000X=100Therefore, total profit = 6x+5x = 11xOr 11 * 100 = 1100 Q.5 A & B enter into the specification A puts in Rs. 50 & B puts in Rs. 45. At the end of 4 months A withdrew half his capital & at the end of 6 months B withdraw half of its capital. C then enters with a capital of Rs. 70. At the end of 12 Months in what ratio will the profit be divided ?A) 80 : 81 : 84B) 82 : 83 : 85C) 86 : 88 : 89D) 91 : 93 : 95Ans. AA = 50 * 4 + 50/2 * 8 : 45*6 + 45/2*6 : 70*6Or 400 :405:450=80:81:84    

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TIME & WORK SET 3

Q.1 If 3 men & 5 women can do a piece of work in 8 days & 2 men & 7 children do the same piece of work in 12 days. How many women can do as much work in a day as 21 children ? A) 15 B) 10 C) 7 D) 12 Ans. B If in 8 days the work can be done by 3 men+5women Therefore, in 1 day the work can be done by 8 (3 men + 5 women)24 men + 40 women Again if in 12 days the work can be done by 2 men + 7 childrenTherefore, if in 1 day the work can be done 12 (2 men + 7 children)24 men + 84 children Work of 24 men & 40 women = work of 24 men & 84 children Work of 84 children = work of 40 women Work of 1 children = work of 40/84 women Therefore, work of 21 children = work of 40*21 / 84 women = work of 10 women Q.2 When Manish alone can do a piece of work , he takes 16 days more than the time taken by Manish & Anuj together to complete the work while Anuj takes 9 days more than the time taken by Manish & Anuj together to complete the work. What time Manish & Anuj together will take to complete the work ? A) 10 days B) 11 days C) 12 days D) 13 days Ans. C Q.3 Number of men can do a piece of work in 24 days. If there were 5 men less the work could be finished in 8 days more. How many men were initially present at the work ? A) 20 B) 21 C) 22 D) 23 Ans. A Shortcut :a(D + d) / di.e. 5 (24 + 10) / 8 = 5*32 / 8 = 20 Q.4 Sunil completes a work in 4 days where Dinesh completes the work in 6 days. Ramesh works 1 ½ times as fast as sunil. Three together can complete the work in: A) 1 5/12 B) 1 5/7 C) 1 3/8 D) 1 5/19 Ans. D Number of days taken by Ramesh = 4*2/3 = 8/3Thus, x=4, y=6, z=8/3Therefore, xyz / xy + yz +zx On Solving, we will get1 5/19 Q.5 Three persons undertake to complete a work inRs.1200. The first person can complete a work in 8 days, second person in 12 days & third person in 16 days. They complete the work with the help of fourth person in 3 days. What does the fourth person get ? A) Rs. 225 B) Rs. 250 C) Rs. 200 D) Rs. 180 Ans. A Let fourth person works in x daysThus, 1/8 + 1/12 + 1/16 + 1/x = 1/3Or 1/x = 1/3- 1/8 -1/12 – 1/16Or 16-6-4-3 / 48 = 3/48 = 1/16Or x=16Now, ratio of work done by first, second, third & fourth person= 1/8 : 1/12 : 1/16 : 1/16 = 6:4:3:3 Thus , Amount by fourth person is: 3/16 * 1200 = Rs.225    

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TIME & WORK SET 2

Q.1 Carpenter A can make chair in 6hrs , Carpenter B in 7 hrs & Carpenter C in 8hrs. If each carpenter works for 8hrs per day, how many chairs will be made in 21 days ?A) 73B) 69C) 61D) 67Ans. AA can make in 21 days= 21*8/6 = 28 chairsB can make in 21 days = 21*8/7 = 28chairsC can make in 21 days=21*8/8 = 21 chairsTherefore total no. of chairs = 28+24+21 = 73chairs Q.2 A & B can complete work together in 5 days. If A works at twice his speed & B at half of his speed , this work can be finished in 4 days. How many days would it take for A alone to complete the job ?A) 10B) 15C) 12D) 18Ans. ALet A can do work in x days & B can do in y daysThus,1/x + 1/y = 1/5—i2/x + 1/2y = ¼—iiNow solve these two equations, we will get2/x + 1/2y=1/44/x + 1/y=1/21/y=1/2 -4/x—–iiiPut the value of 1/y in eq-i1/x+1/y = 1/51/x + ½-4/x = 1/51/x-4/x=1/5-1/2=2-5/10 =-3/10Thus on solving we get,X=10 Q.3 Amit & Saurabh can complete a piece of work in 15 days. If B alone takes 20 days to complete that work. Find the time taken by A alone to complete that work . A) 60 days B) 61 days C) 62 days D) 63 days Ans. A Shortcut:Xy / y-x15*20 / 20-15 = 60 days Q.4 20 men can complete the work in 40 days. When should 4 men leave so that the work may be finished in 48 days ? A) 8 days B) 10 days C) 4 days D) 6 days Ans. A Suppose 4 men leave after x daysTherefore, work done by 20 men in x days = x/40Remaining work = 1- x/4040-x / 40No. of remaining days = 48-xNo. of remaining men = 20-4 = 16If 20 men can do in 40 days 1 workTherefore, 1 men can do in 1 day= 1 / 20*40 16 men can do in 48-x days = 1*16*(48-x) / 20*40Therefore, 16*(48-x) / 20*40 = 40-x / 40192-4x = 200-5xX=8 Q.5 25 Men were employed to do a piece of work which they could finish in 20 days but the men dropped off by 5 at the end of every 10 days. In what time will the work be completed ? A) 23 ½ days B) 8 days C) 26 days D) 17 days Ans. A Work done by 25 men in 1 day = 1/20Therefore, work done by 25 men in 10 days = 1/20 * 10 = ½Therefore, no. of workers available after 10 days= 25-5 = 20Work done by 25 men in 1 day = 1/20Work done by 1 man in 1 day = 1 / 20*25Work done by 20 men in 10 days = 1/20 * 1/25 * 20 * 10=2/5Again, the no. of workers available after 20 days = 20-5 = 15Remaining work = 1 – ½ – 2/5 = 1/10Therefore, 1/20 work is done by 25 men in 1 day 1 work is done by 1 men in = 1*20*251/10 work is done by 15 men in = 1*20*25*1 / 15*10 = 10/3Therefore, total no. of days = 10+10+ 3 1/3=23 1/3  

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TIME & WORK SET 1

Q.1 Lipika reads a book for 1 ¾ hours every day. She reads the entire book in 6 days. How many hours in all were required by her to read the book? A) 16 B) 17 C) 18 D) 19 Ans. D 13/4 * 6/1 13/2 * 3/1 = 39/2 Or 19 Q.2 Suman studies for 5 2/3 hours daily. She devotes 4 2/5 hours of her time for Science and Mathematics. How much time does she devote for other subjects? A) 1 13/15 B) 2 13/15 C) 1 12/15 D) 2 12/15 Ans. B Total time of Suman’s study =5 2/3 hr = 17/3 hr. Time devoted by her for Science and Mathematics = 2 4/5 = 14/5 hr Thus, time devoted by her for other subjects = 17/3 – 14/5 hr 17 * 5 / 15 – 14 * 3/ 15 = 43/15 hr = 2 13/15 hr Q.3 A can complete a work in 20 days & B in 30 days. A worked alone for 4 days & then B completed the remaining work along with C in 18 days. In how many days can C working alone complete the work ? A) 68 days B) 90 days C) 12 days D) 72 days Ans. B Work done by A = 4/20 = 1/5 Therefore remaining work = 1-1/5 = 4/5 Let C working alone can do work in x days Thus, 18/30 + 18/x = 4/5 Or 18(x+30) * 5 =4*30x 90x + 2700 = 120 x 30x = 2700 Or x=90 days Q.4 In a garrison, there was food for 1000 soldiers for one month. After 10 days, 1000 more soldiers joined the garrison. How long would the soldiers be able to carry on with the remaining food ? A) 25 days B) 20 days C) 15 days D) 10 days Ans. D Let the number of days be X Then as per the question:- 1000*(30-10) = (1000+1000)*X 1000*20 = 2000*x X= 20000/2000 X=10 Q.5 If 3 men & 4 boys complete a work in 7 days & 2 men & 3 boys do the same work in 10 days. In how many days will 3 men & 8 boys complete the same work ? A) 5 days B) 6 days C) 7 days D) 8 days Ans. A 3 men & 4 boys complete a work in 7 days 2 men & 3 boys complete a work in 10 days Therefore, 3 men + 4 boys / 2 men + 3 boys = 10 / 7 (Since there is inverse proportional in men & days) 21 men + 28 days = 20 men + 30 boys 1 man = 2 boys 3 men + boys = 6 boys + 4 boys = 10 boys 3 men + 8 boys = 6 boys + 8 boys = 14 boys Boys days 10 7 14 x Or 10 / 14 = x / 7 X = 5 days

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PROBABILITY, PERMUTATION & COMBINATION SET 1

Q.1 A bag contains four black and five red balls, if three balls are picked at random one after another WITH replacement, what is the chance that they’re all black? A) 64/729 B) 64/730 C) 63/729 D) 63/730 Ans. A With replacement means you pick up a ball note down its color and then put it back in the bag again. So Total Number of balls remain same for each event. And Hence probability of picking a black ball (4/9) remains the same in every case. 1st Pick up:4/9; 2nd Pick up: 4/9 ;because we put the ball back in the bag, So probability is same as “1st Pick”. 3rd Pick up: 4/9 ;because we put the ball back in the bag. So final probability =1st x 2nd x 3rd =4/9 x 4/9 x 4/9 =Cube of 4/9 =64/729 Q.2 If you have a spinning wheel with 3 green sectors, 1 blue sector and 1 red sector, what is the probability of getting a green sector? What is the probability of getting a non blue sector? A) Green = 3/5 ; Non-blue = 4/5 B) Green = 2/5 ; Non-blue = 3/5 C) Green = 4/5 ; Non-blue = 3/5 D) Green = 3/5 ; Non-blue = 2/5 Ans. A Total number of events = 5 Q.3 A bag has 4 red balls and 2 yellow balls. (The balls are identical in all respects other than colour). A ball is drawn from the bag without looking into the bag. What is probability of getting a red ball? A) 2/3 B) 2/4 C) 2/5 D) 2/6 Ans. A There are in all (4 + 2 =) 6 outcomes of the event. Getting a red ball consists of 4 outcomes. Therefore, the probability of getting a red ball is 4/6 = 2/3 Q.4 There are 100 students in a particular class. 60% students play cricket, 30% student play football and 10% students play both the games. What is the number of students who play neither cricket nor football? A) 25 B) 20 C) 18 D) 15 Ans. B 100- (50+20+10) = 100-80 = 20 Q.5 In a group of persons, 70% of the persons are male and 30% of the persons are married. If two-sevenths of the males are married, what fraction of the females is single? A) 2/7 B) 1/3 C) 3/7 D) 2/3 Ans. D Let total no. of persons =100 Therefore total no. of males= 70 Total no. of females= 30 Given that, no. of unmarried persons =30 So, Number of married males= 2/7 * 70=20 Therefore, No. of married females =30-20 =10 Therefore, No. of unmarried females =30-10 = 20 Therefore, Required fraction of single females= 20/30 = 2/3

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PASSAGE 44

A stout old lady was walking with her basket down the middle of a street in Petrograd to the great confusion of the traffic and no small peril to herself, It was pointed out to her that the pavement was the place for foot-passengers, but she replied, “I’m going to walk where I like, We’ve got liberty now”, It did not occur to the dear lady that if liberty entitled the foot-passenger to walk down the middle of the road it also entitled the taxi-driver to drive on the pavement, and that the end of such liberty would be universal chaos, Everything would be getting in everybody else’s way and nobody would get anywhere, Individual liberty would have become social anarchy. 1. It was pointed out to the lady that she should walk on the pavement because she wasa) a pedestrianb) carrying a basketc) stoutd) an old lady 2. The lady refused to move from the middle of the street becausea) she was not afraid of being killedb) she felt that she is entitled to do whatever she likedc) she did not like walking on the pavementd) she was confused 3. The old lady failed to realize thata) she was not really freeb) her liberty was not unlimitedc) she was an old persond) roads are made for motor vehicles only   ABB    

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PASSAGE 43

It was already late when we set out for the next town, which according to the map was about fifteen kilometers away on the other side of the hills, There we felt that we would find a bed for the night. Darkness fell soon after we left the village, but luckily we met no one as we drove swiftly along the narrow winding road that led to the hills, As we climbed higher, it became colder and rain began to fall, making it difficult at times to see the road, I asked John, my companion, to drive more slowly, After we had travelled for about twenty Kilometers, there was still no sign of the town which was marked on the map, We were beginning to get worried, Then without warning, the car stopped and we found we had run out of petrol. 1. The author asked John to drive more slowly becausea) the road led to the hillsb) John was an inexperienced driverc) the road was not clearly visibled) they were in wilderness 2. The travelers set out for the town although it was getting dark becausea) they were in a hurryb) the next town was a short distance away and was a hill-resortc) they were in wildernessd) the next town was a short distance away and promised a goo and rest for the night 3. The travelers were worried after twenty kilometers becausea) it was a lonely countrysideb) they probably feared of having lost their wayc) the rain began to falld) it was getting colder as they drove   CDB  

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PASSAGE 42

Seven-year-old Jim came home from the park without his new bicycle. “An old man and a little boy borrowed it”, he explained. “They are going to bring it back at four o’clock”. His parents were upset that he had given his expensive new bicycle, but were secretly proud of his kindness and faith. Came four o’clock, no bicycle. The parents were anxious. But at 4:30, the door bell rang, and there stood a happy man and a boy, with the bicycle and a box of chocolates. Jim suddenly disappeared into his bedroom, and then came running out. “All right”, he said, after examining the bicycle. “You can have your watch back!” 1. When Jim came home without his bicycle, his parentsa) were angry with himb) were worriedc) did not feel concernedd) were eager to meet the old man and the little boy 2. Jim returned the watch to the old man and the little boy becausea) they gave him chocolates.b) his father was proud of him.c) he was satisfied with the condition of his bicycle.d) they were late only by 30 minutes.   BC    

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