Average (Railway Maths) (Part – III)

Total Questions: 35

1. The average of 3 consecutive natural numbers (which are in increasing order) is K. If two more consecutive numbers, just next to the first set of numbers, are added, then the new average will become: [RRB NTPC 24/07/2021 (Evening) ]

Correct Answer: (a) K + 1
Solution:

2. From every perfect square NOT exceeding 101, Rahul subtracts 5. What is the average of the numbers Rahul obtained? [RRB NTPC 26/07/2021 (Evening)]

Correct Answer: (c) 33.5
Solution:

3. Consider the average of any five consecutive odd natural numbers as p. If two more consecutive odd numbers, just next to the previous five numbers, are added, then the new average will become: [RRB NTPC 31/07/2021 (Morning)]

Correct Answer: (d) p + 2
Solution:

4. Out of 40 students, 15 are boys. In a test, the mean marks of the class is 75 and the average marks of the girls is 72. What is the average marks of boys ? [RRB JE 26/06/2019 (Evening) ]

Correct Answer: (a) 80
Solution:

Total number of student in the class = 40, Boys = 15, so girls = 25
Mean marks of the class = 75. so, total marks = 40 × 75 = 3000
Now average marks of the girls = 72 so, total marks obtained by girls = 25 × 72 = 1800
Therefore total marks obtained by boys = 3000 - 1800 = 1200
∴ average marks of the boys
= total marks obtained by boys / total boys
= 1200 / 15 = 80
Short Tricks :-

5. The average of 5 numbers is 113. Even after one number is excluded, the average remains the same. Find out the number dropped out of it. [RPF Constable 17/01/2019 (Morning)]

Correct Answer: (d) 113
Solution:

6. To win a competition, Swami needs an average of 80 marks in four exams. His marks in the first three exams are 68, 78 and 88. How many marks should he get in the fourth test to win the competition? [RPF Constable 17/01/2019 (Morning)]

Correct Answer: (a) 86
Solution:

7. Five numbers have an average of 126. The average does not change even after a number is excluded. What is the value of the excluded number? [RPF Constable 17/01/2019 (Evening)]

Correct Answer: (a) 126
Solution:

8. In order to qualify for a competition, Haumi will have to score an average of 80 marks in four examinations. She got 81, 91 and 66 marks in the first three examinations. How many marks will she have to score in the fourth test to qualify for the competition? [RPF Constable 17/01/2019 (Evening)]

Correct Answer: (c) 82
Solution:

9. To win a competition, Swami needs an average of 80 marks in four exams. Her marks in the first three examinations are 74, 84 and 94. How many marks should he get in the fourth test to win the competition? [RPF Constable 18/01/2019 (Afternoon)]

Correct Answer: (c) 68
Solution:

10. The average of 5 numbers is 119. One number is removed from the group but the average remains the same. Find out the removed number. [RPF Constable 18/01/2019 (Afternoon)]

Correct Answer: (c) 119
Solution: