WBCS MATHS

Diagonal of the floor of a rectangular closet is 7.5 feet. The shorter side of the closest is 4.5 feet. What is the area of the closet in sq feet.

Solve:

The percentage increase in the area of a rectangle, if each of its sides is increased by 20%

Solve:
Let each side of the rectangle is 10 , therefore area is 10×10= 100 unit. Now side is 12 and area is 12×12=144 unit. Area increase, 144-100= 44 unit. 44% increase.

Ajit has certain average for 9 innings. In the tenth innings, he scores 100 runs thereby increasing his average by 8 runs. His new average is:

Solve: 100 - (9×8) = 28 years

How many square are there:

a) 15 b) 17 c) 19 d) 21

Comment the answer.

Two pipes P and Q can fill a cistern in 12 and 15 minutes respectively. Both are opened together, but at the end of 3 minutes, p turned off. In how many more minutes will Q fill the cistern?

Solve:

Let total capacity of the tank, (Lcm of 12 & 15) is 60 unit.

Therefore capacity of P & Q is 5 , 4 unit respectively.

In 3 minutes P&q together can fiil 9×3 = 27 units.
Rem. 60 - 27=33 unit filled by Q in 33/4 minutes.

A man covers half of his journey at 6 km/h and the remaining half at 3 km/h. His average speed is.

Solve:

Trick: When same distance covers twice in different speed,
The average speed = 2×X×Y/X+Y

Here average speed of the man is:
2×6×3/6+3
=2×6×3/9
= 4 km / hour.

The speed of A and B are in the ratio 3:4. A takes 20 minutes more than B to reach a destination. Time in which A reach the destination?

Solve: Speed ratio A : B - 3 : 4
Therefore time ratio - 4 : 3

When Ratio difference is 1 time difference is 20 minutes.

As time ratio of A is 4 . A takes 4×20 = 80 minutes.

A hall 25 metres long and 15 metres broad is surrounded by a varandah of uniform width of 3.5 metres. The cost of flooring the varandah, at Rs. 27.50 per square metre is

A and B together can complete a work in 18 days, A and C together in 12 days, and B and C together in 9 days, then B alone can do the work in:

A and B together can complete a work in 3 days. They start together but after 2 days, B left the work. If the work is completed after two more days, A alona could do the work in