10
Q:

# The ratio of speeds of a car, a train and a bus is 5:9:4. The average speed of the car, the bus and the train is 72 km/hr together. What is the average speed of the car and the train together ?

 A) 84 km/hr B) 96 km/hr C) 72 km/hr D) 60 km/hr

Explanation:

Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively.
Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr.
Also, 6x = 72 => x = 12 km/hr
Therefore, the average speed of the car and train together is = $\frac{5x+9x}{2}$= 7x = 7 x 12 = 84 km/hr.

Q:

Third proportion of 10 and 20 is

 A) 30 B) 40 C) 25 D) 20

Explanation:

The third proportional of two numbers p and q is defined to be that number r such that

p : q = q : r.

Here, required third proportional of 10 & 20, and let it be 'a'

=> 10 : 20 = 20 : a

10a = 20 x 20

=> a = 40

Hence, third proportional of 10 & 20 is 40.

2 257
Q:

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?

 A) 54.21 kgs B) 51.07 kgs C) 52.66 kgs D) 53.45 kgs

Explanation:

Given total number of passengers in the bus = 45

First average weight of 45 passengers = 52 kgs

Average weight of 5 passengers who leave bus = 48

Average weight of passengers who joined the bus = 54

Therefore, the net average weight of the bus is given by

15 1113
Q:

12 boys decided to constribute Rs. 750 each to an Orphange. Suddenly few of them boys dropped out and consequently the rest had to pay Rs. 150 more. Then the number of boys who dropped out?

 A) 4 B) 6 C) 2 D) 3

Explanation:

Total money decided to contribute = 750 x 12 = 9000

Let 'b' boys dropped

The rest paid 150/- more

=> (12 - b) x 900 = 9000

=> b = 2

Hence, the number of boys who dropped out is 2.

14 1291
Q:

P, Q, R, S, T and U are six consecutive odd numbers and their average is 52. What is the product of P and U ?

 A) 2212 B) 2154 C) 2349 D) 2679

Explanation:

Let x, x+2, x+4, x+6, x+8 and x+10 are six consecutive odd numbers.

Given that their average is 52

Then, x + x+2 + x+4 + x+6 + x+8 + x+10 = 52×6

6x + 30 = 312

x = 47

So Product = 47 × 57 = 2679

13 1353
Q:

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?

 A) Rs. 1398.96 B) Rs. 1457.09 C) Rs. 1662.35 D) Rs. 1536.07

Explanation:

Let average expenditure was Rs. R

13 x 79 + 6x(R + 4) = 19R

=> R = Rs. 80.84

Total money = 19 x 80.84 = Rs. 1536.07.

19 1215
Q:

The average age of a class is 19 years. While the average age of girls is 18 and that of boys is 21. If the number of girls in the class is 16, Find the number of Boys in the class?

 A) 12 B) 10 C) 8 D) 6

Explanation:

Let the number of boys = x

From the given data,

=> [21x + 16(18)]/(x+16) = 19

=> 21x - 19x = 19(16) - 16(18)

=> 2x = 16

=> x = 8

Therefore, the number of boys in the class = 8.

13 1443
Q:

The mean of 100 observations is 40. It is found that an observation 84 was misread as 48. Then the correct mean is ?

 A) 40.36 B) 41.24 C) 41.92 D) 42.05

Explanation:

Given,

mean of 100 observations is 40

=> Total of 100 observations = 40 x 100 = 4000

=> Difference = 84 - 48 = 36

=> Now, new total of 100 observations = 4000 + 36 = 4036

Correct Mean = 4036/100 = 40.36

16 1748
Q:

The average marks of a student in 7 subjects is 85. His average marks in 6 subjects except English is 83. What is his marks in English ?

 A) 97 B) 98 C) 92 D) 93