Mathematics MCQs

A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is?

by
A. 6 hrs
B. 10 hrs
C. 15 hrs
D. 30 hrs
✅ The correct answer is option C. 15 hrs.

The denominator of a fraction is 1 less than twice the numerator. If the numerator and denominator are both increased by 1, the fraction becomes 3/5. Find the fraction?

by
A. 2/3
B. 3/5
C. 4/7
D. 5/9
✅ The correct answer is option D. 5/9.
Let the numerator and denominator of the fraction be ‘n’ and ‘d’ respectively.

d = 2n – 1

(n + 1)/(d + 1) = 3/5

5n + 5 = 3d + 3

5n + 5 = 3(2n – 1) + 3 => n = 5

d = 2n – 1 => d = 9

Hence the fraction is : 5/9.