Aptitude Questions : Averages Set 6

Hello Aspirants. Welcome to Online Quantitative Aptitude Section with explanation in AffairsCloud.com. Here we are creating question sample in Averages, which is common for all the IBPS, SBI exam and other competitive exams. We have included Some questions that are repeatedly asked in bank exams !!!

1. While calculating the weight of a group of men, the weight of 63 kg of one of the member was mistakenly written as 83 kg. Due to this the average of the weights increased by half kg. What is the number of men in the group?
   A) 25
   B) 20
   C) 40
   D) 60
   E) 24
   
   Answer & Explanation

   C) 40
   Explanation:
   Increase in marks lead to increase in average by ½
   So (83-63) = x/2
   x = 40
   
   
   
2. A cricketer had an average number of runs as 32 after playing 10-innings. If he wants to make his average run rate increased by 4, then how much runs will he have to take in his next inning?
   A) 66
   B) 84
   C) 62
   D) 76
   E) 72
   
   Answer & Explanation

   D) 76
   Explanation:
   Average after 10 innings = 32, so after 11 inning = 32+4 = 36
   So required runs = (36*11) – (32*10)
   
   
3. The average temperature in Delhi for the first four days of the month was reported as 58^o. It reported as 60^o for 2nd, 3rd, 4th and 5th days. The ratio of the temperatures of 1st and 5th day was 7 : 8. Find the temperature on the first day.
   A) 42^o
   B) 46^o
   C) 63^o
   D) 68^o
   E) 56^o
   
   Answer & Explanation

   E) 56^o
   Explanation:
   A+B+C+D = 58*4
   B+C+D+E = 60*4
   Subtract both, E – A = 8
   So 8x – 7x = 8, x = 8
   So temperature of A(1st day) = 7x = 7*8
   
   
4. For three successive years, the cost of petrol were Rs 20 per litre, Rs 22 per litre and Rs 23.50 per litre respectively. If a man spent an average of Rs 8000 per year on petrol, then he spent what average cost of petrol per litre for the three years?
   A) Rs 20
   B) Rs 25.3
   C) Rs 28.2
   D) Rs 21.7
   E) None of these
   
   Answer & Explanation

   D) Rs 21.7
   Explanation:
   Quantity used in 1st yr = 8000/20 = 400 l, in 2nd yr = 8000/22 = 363.6, in 3rd yr = 340.4 l
   Total used in 3 yrs = 1104 litres, total money spent in 3 yrs = 3*8000 = 24000
   So average rate of 3 yrs = 24000/1104
   
   
   
5. In a group of 8 boys, 2 men aged at 21 and 23 were replaced two new boys. Due to this the average cost of the group increased by 2 years. What is the average age of the 2 new boys?
   A) 17
   B) 30
   C) 28
   D) 23
   E) 18
   
   Answer & Explanation

   B) 30
   Explanation:
   Average of 8 boys increased by 2, this means the total age of boys increased by 8*2 = 16 yrs
   So sum of ages of two new boys = 21+23+16 = 60
   Average of these = 60/2
   
   
   
6. The average age of the group having 3 members is 84. One more person joins the group and now the average becomes 80. Now a fifth person comes whose age is 3 years more than that of fourth person replaces the first person. After this the average age of the group becomes 79. What is the weight of the first person?
   A) 75
   B) 65
   C) 68
   D) 82
   E) 85
   
   Answer & Explanation

   A) 75
   Explanation:
   Let the ages of these are A, B, C, D, E
   So A+B+C = 84*3 = 252
   And A+B+C+D = 80*4 = 320
   So D = 320-252 = 68, so E = 68+3 = 71
   Now B+C+D+E = 79*4 = 316
   (A+B+C+D) – (B+C+D+E) = 320- 316
   So A-E = 4, so A = 71+4
   
   
7. 3 years ago, the average age of A, B, and C was 27 years. Also 5 years ago, the average age of B and C was 20 years. What is the present age of A?
   A) 42
   B) 40
   C) 34
   D) 35
   E) 48
   
   Answer & Explanation

   B) 40
   Explanation:
   Sum of ages of A+B+C 3 yrs ago = 27*3 = 81
   So after 3 yrs, i.e. at present their total = 81 + 3*3 = 90
   Similarly sum of present age of B&C = 20*2 +5*2 = 50
   So present age of A = 90-50
   
   
8. Average age of girls in a class is 16 years. If the average of the boys in class is also added, the average becomes 15.5 years. If there were 20 boys in the class with average age 15 years, how many girls were there in the class?
   A) 15
   B) 40
   C) 20
   D) 25
   E) 30
   
   Answer & Explanation

   C) 20
   Explanation:
   Let x girls in the class, so
   16x + 20*15 = 15.5 (x+20)
   
   
9. In a class, the average marks got by number of students in English is 52.25. 25% students placed in C category made the average of 31 marks, while 20% who were placed in A category made the average of 80 marks. Find the average marks of the remaining students?
   A) 50
   B) 52.2
   C) 51
   D) 51.8
   E) 48.8
   
   Answer & Explanation

   D) 51.8
   Explanation:
   Let there are 100 students in the class, then in category A = 20 students, in C = 25 students, remaining = 55 students. Let x be the average of these 55 students.
   So 20*80+ 25*31 + 55*x = 52.25*100
   
   
10. The average of 5 numbers is 40. Average of first two and last two is 25 and 45 respectively. Find the middle number.
    A) 60
    B) 45
    C) 30
    D) Cannot be determined
    E) None of these
    
    Answer & Explanation

    A) 60
    Explanation:
    5*40 – (2*25 + 2*45)