AVERAGE MCQS

Q.1 Four years ago, the average age of four friends was 25 years. Now, with a fifth friend joining the group, their average is 24 years. What is the present age of the new friend? A) 20 yrs B) 21 yrs C) 36 yrs D) 24 yrs Ans. A Total age of all friends including new friend = 24 5 = 120 years Present age of the new friend = new average age – old average age 120 – 100 = 20 years.   Q.2 Gavaskar’s average in his first 50 innings was 50. After the 51st innings, his average was 51. How many runs did he score in his 51st innings. (supposing that he lost his wicket in his 51st innings) A) 101 B) 102 C) 103 D) 104 Ans. A Explanation : Total score after 50 innings = 50*50 = 2500 Total score after 51 innings = 51*51 = 2601 So, runs made in the 51st innings = 2601-2500 = 101 If he had not lost his wicket in his 51st innings, he would have scored an unbeaten 50 in his 51st innings.   Q.3 In a class the average age is 16yrs.If the teacher who is 40 yrs of age is also included ,the average becomes 17yrs,how many students were there? A) 21 B) 22 C) 23 D) 24 Ans. C 40 – 17 = 23 students   Q.4 Average salary of 100 employees in an office is Rs.16000 /month. Management decided to raise salary of every employee by 5% but stopped a transport allowance of Rs. 800 /month which was paid earlier to every employee. What will be the average monthly salary ? A) Rs.16500 B) Rs. 16000 C) Rs. 16800 D) Can’t be determined Ans. B Increament = 5% of 16000 16000*5/100 = Rs. 800 Therefore incremented salary = 16000+800 = 16800 New salary after deducting transport allowance = 16800-800 =Rs. 16000   Q.5 Average marks obtained by the 120 candidates in a certain exam is 35. If the average marks of the passed candidates is 39 & that of the failed candidates is 15. What is the no. of candidates passed the exams ? A) 100 B) 200 C) 120 D) 220 Ans. A Shortcut: No. of passed candidates = Total Candidates (Total average – Failed average) / Passed average – Failed Average Therefore, 120*(35-15) / 39-15 =100

Q.1 Average marks in a class of 30 students are found to be 45. On checking two mistakes were found. After correction if one student got 45 marks more & another student got 15 marks less, then the corrected average marks are : A) 47 B) 44 C) 46 D) 45 Ans. C Total marks of 300 students before correction = 30*45 = 1350 & total marks of 30 students after correction = 1350+45-15 = 1380 Therefore, corrected average marks 1380/30 = 46   Q.2 Average salary of entire staff in an office is Rs. 120 per month. The average salary of officers is Rs. 460 & that of non-officers is Rs. 110. If the number of officers is 15, then find the number of non-officers in the office ? A) 500 B) 550 C) 510 D) 445 Ans. C Let number of non-officers be x 110x + 460 * 15 = 120(15+x) 120 – 110x = 460*15 – 120*15 = 15(460-120) 10x = 15*340 X= 15*34 = 510   Q.3 A cricketer has completed 10 innings & his average is 21.5 runs. How many runs must he make in his next Innings so as to raise his average to 24 ? A) 25 B) 45 C) 30 D) 49 Ans. D 10 (24 – 21.5) + 24 = 25 + 24 = 49   Q.4 Rahina did a Mathematic test. In this test Each correct answer scored 8 marks & each incorrect answer reduced score by 4 marks. The test contained 30 Questions & after completing it ,Rahina had a score of Zero. How many Questions did she answer correctly ? A) 8 B) 10 C) 15 D) 12 Ans. B 8x – 4y = 0 X + y = 30 On solving, We get x = 10   Q.5 A tree is 8.4 m tall, another is half its height and the third one is its quarter. What is the average height of the trees? A) 4.55 m B) 4.6 m C) 4.9 m D) 4.8 m Ans. C Height of the first tree = 8.4 m tall Height of the second tree = ½ 8.4 = 4.2 m Height of the third tree = ¼ 8.4 = 2.1 m Total height = 8.4 + 4.2 + 2.1 = 14.7 Average height = = 4.9 m

Q.1 Average weight of 8 persons is increased by the 2.5kg when one of the weights 56kg is replaced by a new man. Find the weight of a new man ? A) 76 kg B) 77 kg C) 78 kg D) 79 kg Ans. A Shortcut: Weight of new comer = Previous weight + No. of persons*Increase in average weight Therefore, 56+8*2.5 = 76 kg   Q.2 Average age of 30 boys is equal to the 14yrs, when the age of the class teacher is included average becomes 15 years . Find the average of the class teacher ? A) 45 yrs B) 46 yrs C) 47 yrs D) 48 yrs Ans. A Shortcut: Age of new comer = Previous age + No. of persons*Increase in average age 14+31(15-14) =45 Ans.   Q.3 The average age of a group of 15 persons is 29 years. Among them, the age of each of the two persons is 55 years. What is the average age of remaining 13 persons? A) 23 B) 28 C) 26 D) 25 Ans. D 15*29 = 435 2 person of 55kg leaving = 435-110 Therefore new average = 325/13 = 25   Q.4 A man spends his 2 months earning in 3 months & if he saves Rs. 1500 a year, then his monthly income is: A) Rs. 450 B) Rs. 375 C) Rs. 425 D) Rs. 400 Ans. B A man spends his 2 months earning in 3 months & if he saves Rs. 1500 a year, then his monthly income is: Man saves one month’s earning in 3 months Therefore he will save in one year salary of 4 months But his saving in 1 year = Rs. 1500 His 4 month’s earning = Rs.1500 Therefore, His 1 month’s earning = Rs. 375   Q.5 The average score of a cricketer in certain number of innings is 15. When he scored a duck in one innings, his average dropped to 13.5. How many innings has he played in total, including the latest one? A) 13 B) 10 C) 11 D) 9 Ans. B Let the number of innings = x Total runs scored by the player = 15x New number of innings = x + 1 Also new average = = 13.5 ? 15x = 13.5x + 13.5 ? 1.5x = 13.5 ? x = 9. Number of innings played including the latest one = 9 + 1 = 10

Q.1 A student on her first 3 tests received an average score of N points. If she exceeds her previous average score by 20 points on her fourth test, then what is the average score for the first 4 tests? A) N + 20 B) N + 10 C) N + 4 D) N + 5 Ans. D Required Average= 4N+20/4 = 4N/4 + 20/ = N+5   Q.2 If the weight of a group of 20 boys was calculated to be 89.4 kg& it was later discovered that one weight was misread as 78 kg instead of the correct one of 87 kg. Then the correct average weight (in kg ) is: A) 89.25 B) 89.85 C) 88.95 D) 89.55 Ans. B Total weight of 20 boys which is wrong = 89.4 * 20 = 1788 kg Therefore, correct weight of 20 boys = 1788 – 78 + 87 = 1797 kg Therefore, correct average weight = 1797 / 20 = 89.85 kg   Q.3 Average salary of 100 employees in an office is Rs.16000 /month. Management decided to raise salary of every employee by 5% but stopped a transport allowance of Rs. 800 /month which was paid earlier to every employee. What will be the average monthly salary ? A) Rs.16500 B) Rs. 16000 C) Rs. 16800 D) Can’t be determined Ans. B Increament = 5% of 16000 16000*5/100 = Rs. 800 Therefore incremented salary = 16000+800 = 16800 New salary after deducting transport allowance = 16800-800 =Rs. 16000   Q.4 Average marks obtained by the 120 candidates in a certain exam is 35. If the average marks of the passed candidates is 39 & that of the failed candidates is 15. What is the no. of candidates passed the exams ? A) 100 B) 200 C) 120 D) 220 Ans. A Shortcut: No. of passed candidates = Total Candidates (Total average – Failed average) / Passed average – Failed Average Therefore, 120*(35-15) / 39-15 =100   Q.5 A man spends on an average Rs.450 for the first 8 months & Rs. 475 for the next 4 months. If he saves Rs.500. What is the monthly salary? A) 300 B) 400 C) 500 D) 600 Ans. C 450*8 = 3600 475*4 = 1900 Therefore, total expenditure = Rs.500 But saving is : 500 Thus total salary is=6000 So, Monthly salary = 6000/2 = 500 Rs.