RRB NTPC Mathematics 2 — Questions and Answers
Question 1: The average of five consecutive odd numbers is 25. The largest number is:
- 27
- 29 (Correct answer)
- 31
- 23
Correct answer: 29
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?
- 24 hours (Correct answer)
- 14 hours
- 20 hours
- 12 hours
Correct answer: 24 hours
Net rate = 1/6 − 1/8 = 1/24, so the tank fills in 24 hours.
Question 3: √(144) + √(81) = ?
- 20
- 21 (Correct answer)
- 23
- 25
Correct answer: 21
√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:
- 24 (Correct answer)
- 42
- 28
- 32
Correct answer: 24
Difference corresponds to 3 parts = 18, so 1 part = 6; smaller number = 4 × 6 = 24.
Question 5: What is 15% of 240?
- 30
- 36 (Correct answer)
- 32
- 40
Correct answer: 36
15% of 240 = (15/100) × 240 = 36.
Question 6: A car covers 150 km in 2.5 hours. How long will it take to cover 300 km at the same speed?
- 4 hours
- 5 hours (Correct answer)
- 6 hours
- 4.5 hours
Correct answer: 5 hours
Speed = 150/2.5 = 60 km/h; time for 300 km = 300/60 = 5 hours.
RRB NTPC Mathematics 2
The average of five consecutive odd numbers is 25.
The largest number is: