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# PERCENTAGE & RATIO PROPORTION SET4

Q.1 In Delhi University, some students appeared for the papers of ten subjects, each constituting of 100 marks. A student has to score 50 marks in order to pass in a subject i.e. overall one need to score fifty percent of the total marks. Find the probability of overall passing of a student, if he got failed in eight subjects?
A) 1457/13231
B) 1458/13232
C) 1459/13234
D) 1460/13235
Ans. A
Range of the marks in the subjects in which the student has failed = 0 – 392.
Range of the marks in the subjects in which the student has passed = 100 – 200
Total possibilities of total marks = 393 × 101 = 39693
Possibilities in which he is passing (scoring 500 marks) are as follows.
(108 and 392), (109, 391), (110, 390) ………… (200, 300)
There are a total of 93 cases, when sum of the marks is 500.
In the same way, there are 92 cases when sum of the marks is 501.
In the same way, there are 91 cases when sum of the marks is 502.
.
.
.
In the same way, there is 1 case when sum of the marks is 592.
So, total number of cases in which he is pass = (1+93)/2 × 93 = 4371
Probability = 4371/39693 = 1457/13231

Q.2 From the salary of a person 10% is deduced as house rent. He spends 15% of the rest on children’s education and 10% of the balance on clothes. After this expenditure, he is left with \$1377. What is his salary?
A) \$2200
B) \$2000
C) \$1900
D) \$1840

Ans. B

Let x be the total salary.
According to the question,

On solving for x, we get x = \$2000

Q.3 When processing flower-nectar into honey by honey bees, considerable amount of water gets reduced. How much flower nectar must be processed to yield 1kg honey if nectar contains 50% water & honey obtained from this nectar contains 15% water.
A) 1.4 kg
B) 1.5 kg
C) 1.6 kg
D) 1.7 kg
Ans. D
Flower nectar contains 50% of non-water part
In honey non-water part contains 85% (100-15)
Therefore, 0.5*amount of flower nectar=0.85*amount of honey=0.85*1kg
Therefore, amount of flower-nectar needed=0.85/0.5*1kg=1.7kg

Q.4 Ravi had 500Rs. & he wanted to lend it out to Manish & Siddharth. Manish is willing to give double rate of interest that Siddharth is willing to give. If Siddharth gives 15% & Ravi wants to double his money in 5 years. How should Ravi split his money ?
A) 2 : 1
B) 3 : 1
C) 1 : 2
D) 1 : 3
Ans. A
Ravi wants to double in 5 years, then
100/5 = 20%
15% 30%
20%
10 5
=2 :1

Q.5 In what ratio should rice of Rs. 10 & Rs.15 & 20 should be mixed to get price of Rs.17/kg ?
A) 1:1:3
B) 2:1:1
C) 3:1:1
D) 1:1:2
Ans. A
10 20 15 20
17 17
3 7 3 2
3:3:9
In this we have taken 9, because of Rs.20 kg
Or 1:1:3