Solve these average problems to score well

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. MODEL: When someone replaces by others EXAMPLES 1. The average weight of 3 women is increased by 4 kg when one […]

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.

MODEL: When someone replaces by others

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EXAMPLES

1. The average weight of 3 women is increased by 4 kg when one of them, whose weight is 100 kg, is replaced by another woman, what is the weight of the new woman?
a) 100 kg b) 102 kg c) 104 kg d) 112 kg
Ans: d
Solution: W1 W2 W3 (= 100 kg)
w
When W3 is replaced by W the average increased by 4 kg
That means this new woman gives 4 kg to each woman
4 4 4 100 = 112 kg

2. The average weight of 15 persons is increased by 2 kg. When in place of a person having weight 70 kg another new person is included, the weight of the new person is
a) 84 kg b) 90 kg c) 98 kg d) 100 kg
Ans: d
Solution: P1, P2, …..P14, P15 (70 kg)
x kg
2 × 15 = 30 kg
70 30 = 100 kg

3. In a class there are 18 students whose average decreased by 2 months, when students aged 12, 13, and 14 years respectively are replaced by the same number of students. Find the average age of the new students.
a) 14 years b) 12 years c) 16 years d) 18 years
Ans: b
Solution: S1, S2 ………..S16, S17, S18
(=12), (=13), (=14)
x y z
18 × 2/12 = 3 years
(12 13 14) – 3 = 36
Average of new students =
36/3 = 12

4) In a class, there are 24 boys whose average age is decreased by 3 months. When 1 boy aged 20 years is replaced by a new boy. Find the age of a new boy.
a) 14 years b) 18 years c) 16 years d) 17 years
Ans: a
Solution: 20 – (24 × 3/12)
=>; 20 – 6 = 14 years