CAT 2018 Question Paper Shift 2 Solved Paper

Let x be the time, on a 24 hours clock, at which the tank is empty.
Time taken by pipe A alone to fill the tank is (20−x) hrs.
Time taken by pipe B alone to fill the tank is (18−x) hrs.
On the other day, A fill the tank for (15−x) hrs and B for 2hrs.
Let A and B be the rate of works of pipe A and B respectively.
⇒‌

A

B

=‌

2

3

⇒(20−x)2=(18−x)3
⇒(20−x)A=1
Let (20−x)A=1
A=‌

1

6

B=‌

1

4

When both work simultaneously, time taken
=‌

1

1 6 +‌ 1 4

=2.4hrs=2hrs24min
The tank will be filled by 16: 24i.e..4: 24pm