Question Detail

In a class, there are 18 boys who are over 160 cm tall. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class ?

Answer: Option B

Explanation:

Let the number of boys be x.
Then, 3/4 x = 18
=> x = 24

If total number of students is y, then
2/3 y = 24
=> y = 36

Number of girls in class = y - x
= 36 - 24 = 12

1. A shepherd had 27 sheep. All but 10 died. How many he left with ?

Answer: Option A

Explanation:

"All but 10 died" means all except 10 died, so he is remained with 10 sheep.

2. If 100 cats kill 100 mice in 100 days, then 4 cats would kill 4 mice in how many days ?

4 day
10 day
40 day
100 day

Answer: Option D

3. First bunch of bananas has (1/4) again as many bananas as a second bunch. If the second bunch has 3 bananas less than the first bunch, then the number of bananas in the first bunch are

Answer: Option D

Explanation:

Let the number of bananas in the second bunch be x.
Then, the number of bananas in the first bunch
= x + 1/4 x
= 5/4 x
So,
5/4 x - x = 3
=> 5x - 4x = 12
x = 12

Number of bananas in first bunch
= 5/4 * 12 = 15

4. A father is now three times as old as his son. Five years back, he was four times as old as his son. The age of the son is :

Answer: Option B

Explanation:

Let son's age be x then father's age is 3x
Five years ago, father's age = 3x-5 and son's age x-5
So, 3x-5 = 4(x-5)
=> 3x-5 = 4x-20
=> x = 15

5. A is three times as old as B. C was twice-as old as A four years ago. In four years' time, A will be 31. What are the present ages of B and C ?

9, 46
9, 50
10, 46
10, 50

Answer: Option B

Explanation:

As from the question we have,
A = 3B --- (i)
c - 4 = 2(A+4) ---(ii)

Also, A + 4 = 31
or A = 31-4 = 27

Putting A = 27 in (i) we get
B = 9
Putting A = 27 in (ii) we get
C = 50