RRB NTPC Mathematics 2

Question 1

The average of five consecutive odd numbers is 25. The largest number is:

Accepted Answer

29

Answer

If the middle number is 25, the five numbers are 21, 23, 25, 27, 29, so the largest is 29.

Question 2

A pipe can fill a tank in 6 hours and another can empty it in 8 hours. If both are open, how long to fill the tank?

Accepted Answer

24 hours

Answer

Net rate = 1/6 − 1/8 = 1/24, so the tank fills in 24 hours.

Question 3

√(144) + √(81) = ?

Accepted Answer

21

Answer

√144 = 12 and √81 = 9, so 12 + 9 = 21.

Question 4

Two numbers are in the ratio 4:7. If their difference is 18, the smaller number is:

Accepted Answer

24

Answer

Difference corresponds to 3 parts = 18, so 1 part = 6; smaller number = 4 × 6 = 24.

Question 5

What is 15% of 240?

Accepted Answer

36

Answer

15% of 240 = (15/100) × 240 = 36.

RRB NTPC Practice Test