average aptitude question and answers -Page 23

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1. The average weight of 45 passengers in a bus is 52 kg. 5 of them whose average weight is 48 kg leave the bus and other 5 passengers whose average weight is 54 kg join the bus at the same stop. What is the new average weight of the bus?
Options
A. 54.21 kgs
B. 51.07 kgs
C. 52.66 kgs
D. 53.45 kgs

2. A car owner buys petrol at Rs 7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year ?
Options
A. 6.23
B. 7.98
C. 8.97
D. 9.89

3. 19 friends went to a restaurant for a combined weekend dinner party. 13 of them spent Rs. 79 each on their dinner and the rest spent Rs. 4 more than the average expenditure of all the 19. What was the total money spent by them?
Options
A. Rs. 1398.96
B. Rs. 1457.09
C. Rs. 1662.35
D. Rs. 1536.07

4. If the average height of boys in a hall is 180 cm and that of girls is 150 cm. If the average height of the gathering is 165 cm, then find the number of girls present in the hall if the number of boys present in the hall are 78 ?
Options
A. 56
B. 64
C. 87
D. 78

5. The average of six numbers is 3.95. The average of two of them is 3.4, while the average of the other two is 3.85. What is the average of the remaining two numbers ?
Options
A. 3.6
B. 4.6
C. 6.5
D. 7.3

6. If the mean of a, b, c is M and ab + bc + ca = 0, then the mean of a2+b2+c23 is :
Options
A. M
B. 3 M^2
C. 2 (M/3)
D. M^2

Correct Answer: 3 M^2

Explanation:

We have : ( a + b + c) / 3 = M or (a + b + c) = 3M.

Now. ${(a + b + c)}^{2} = {(3 M)}^{2} = 9 M^{2}$ .

$< = > a^{2} + b^{2} + c^{2} + 2 (a b + b c + c a) = 9 M^{2}$

$a^{2} + b^{2} + c^{2} = 9 M^{2}, (a b + b c + c a = 0)$

Required mean = $(\frac{a^{2} + b^{2} + c^{2}}{3}) = \frac{9 M^{2}}{3} = 3 M^{2}$ .

7. In an NGO the daily average wages of 20 illiterate employees is decreased from Rs.25 to Rs.10, thus the average salary of all the literate and illiterate employees is decreased Rs.10 per day. The No. of educated employees working in the NGO is :
Options
A. 15
B. 20
C. 10
D. Data Insufficient

8. A man covers a journey from Meerut to Delhi by a car at an average speed of 40 km/hr. He returns back by scooter with an average speed 24 km/hr. Find his average speed during the whole journey?
Options
A. 32 kmph
B. 27 kmph
C. 30 kmph
D. 31 kmph

9. The average score of boys in an examination in a school is 81 and that of the girls is 83 and the average score of the school is 81.8. Then what will be ratio between the number of girls to the number of boys, in the examination?
Options
A. 3:2
B. 2:3
C. 4:3
D. 3:4

10. A student's average marks in five subjects is 82. If the average marks of first two subject is 86.5 and the average marks of last two subjects is 84. Find the marks of third subject?
Options
A. 69
B. 67
C. 71
D. 73

First 23 24 25 ... 45 .. 66 67 Last

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