64
Q:

# If the ratio of the ages of two friends A and B is in the ratio 3 : 5 and that of B and C is 3 : 5 and the sum of their ages is 147, then how old is B?

 A) 27 Years B) 75 Years C) 45 Years D) 49 Years

Explanation:

The ratio of the ages of A and B is 3 : 5.
The ratio of the ages of B and C is 3 : 5.

B's age is the common link to both these ratio. Therefore, if we make the numerical value of the ratio of B's age in both the ratios same, then we can compare the ages of all 3 in a single ratio.

The can be done by getting the value of B in both ratios to be the LCM of 3 and 5 i.e., 15.

The first ratio between A and B will therefore be 9 : 15 and
the second ratio between B and C will be 15 : 25.

Now combining the two ratios, we get A : B : C = 9 : 15 : 25.

Let their ages be 9x, 15x and 25x.
Then, the sum of their ages will be 9x + 15x + 25x = 49x

The question states that the sum of their ages is 147.
i.e., 49x = 147 or x = 3.

Therefore, B's age = 15x = 15*3 = 45

Q:

The ratio of the number of boys to the number of girls in a school of 640 students, is 5 : 3. If 30 more girls are admitted in the school, then how many more boys should be admitted so that the ratio of boys to that of the girls, becomes 14 : 9.

 A) 30 B) 25 C) 15 D) 20

Explanation:

0 75
Q:

If the base radius of 2 cylinders are in the ratio 3 : 4 and their heights are in the ratio 4 : 9, then the ratio of their volumes is:

 A) 2:1 B) 1:4 C) 1:2 D) 4:1

Explanation:

0 16
Q:

If a : b = 2 : 3 and c : b = 5 : 6, then a : b : c is equal to:

 A) 10 : 15 : 18 B) 6 : 9 : 16 C) 4 : 6 : 5 D) 6 : 9 : 12

Explanation:

0 42
Q:

If a : b = 2 : 5, c: b = 3 : 4, then a : b : c is equal to:

 A) 2 : 5 : 4 B) 6 : 15 : 20 C) 2 : 5 : 3 D) 8 : 20 : 15

Explanation:

0 372
Q:

Two numbers are in the ratio 5 : 7. If the first number is 20, then the second number will be:

 A) 8 B) 22 C) 28 D) 18

Explanation:

3 398
Q:

If x is the mean proportional between 12.8 and 64.8 and y is the third proportional to 38.4 and 57.6, then 2x : y is equal to:

 A) 2 : 3 B) 4 : 5 C) 3 : 4 D) 1 : 2

Explanation:

3 323
Q:

If x is the mean proportional between 12.8 and 64.8 and y is the third proportional to 38.4 and 57.6, then 2x : y is equal to:

 A) 2 : 3 B) 4 : 5 C) 3 : 4 D) 1 : 2

Explanation:

2 472
Q:

If the radius of the circumcircle of an equilateral triangle is 8 cm, then the measure of radius of its incircle is:

 A) 16cm B) 4cm C) 12cm D) 8 cm