What’s the average of these problems?

This article is in continuation to the last article on arithmetic that will aid you in your preparation for government recruitment exams. Here are some practice questions along with solutions on the Average topic. 1) The average age of 14 girls and their teacher’s age is 15 years. If the teacher’s age is excluded the […]

This article is in continuation to the last article on arithmetic that will aid you in your preparation for government recruitment exams. Here are some practice questions along with solutions on the Average topic.

1) The average age of 14 girls and their teacher’s age is 15 years. If the teacher’s age is excluded the average reduces by 1, what is teacher’s age?
a) 35 years b) 32 years c) 30 years d) 29 years
Ans: d
Solution: Teacher’s age = 15 14 × (15 – 14)
= 29 years

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2) A batsman makes a score of 58 runs in the 15 innings and thus, increases his average by 3 runs. What is the average after 15th innings?
a) 12 b) 14 c) 16 d) 18
Ans: c
Solution: 58 – (14 × 3)
58 – 42 = 16 runs

3) The average of 50 numbers is 38. If two numbers namely 45 and 55 discarded, the average of the remaining number is
a) 32.5 b) 35 c) 36 d) 37.5
Ans: d
Solution: Sum of two numbers discarded = 45 55 = 100
50 numbers Average = 38
38 × 2 = 76
45 55 =100
100 – 76 = 24
Decrease in average of remaining numbers = 24/28 = 0.5
Thereforfe, average of remaining numbers = 38 – 0.5 = 37.5

4) The average age of a class is 35 years. 6 new students with an average age of 33 years joined that class, thereby decreasing the average by half year. The original strength of the class was?
a) 14 b) 16 c) 18 d) 20
Ans: c
Solution: x 6 = x 6
Average = 35 Average = 33 Average = 34.5
Average decrease by half year
1/2 × x = 1.5 × 6
x = 15/10 × 6 × 2/1
x = 8

5) Out of 10 teachers of a school, one teacher retires and in his place, a new teacher of age 25 years joins. As a result, average age of teachers is reduced by 3 years. The age of the retired teacher is?
a) 50 b) 55 c) 58 d) 60
Ans: b
Solution: Age of retired man = 25 3 × 10 = 55 years

6) A cricketer whose bowling average is 24.85 runs per wicket, takes 5 wickets for 52 runs and thereby decreases his average by 0.85. The number of wickets taken by him before the last match was?
a) 96 b) 72 c) 64 d) 80
Ans: d
Solution: Earlier wickets Last 5 wickets (5 2/5)
24.85 10.4
24 (24.85 – 0.85)
13.6 : 0.85
1 part ->; 5
16 parts ->; 16 × 5 = 80 wickets

7) The average age of four players is 18.5 years. If the age of the coach is also included, the average age is increased by 20% .The age of coach is?
a) 37 years b) 34 years c) 38 years d) 31 years
Ans: a
Solution: 20/100 × 18.5 = 22.2
22.2 – 18.5 = 3.7
=>; 3.7 × 4 22.2
=>; 14.8 22.2 = 37 years

To be continued
M.Venkat
Director
MVK Publications
Dilsukhnagar
7671002120