Question 10

In a committee there are 15 members. If two members whose ages are 45 years and 55 years are replaced by the two new members, then average age of 15 members is increased by 2 years. What is the average age (in years) of the new members?

Solution

Let average age of 15 members = $$x$$ years

=> Total age of 15 members = $$15x$$

Let sum of ages of 2 new members = $$2z$$, thus average age = $$z=?$$

According to ques,

=> $$\frac{15x-45-55+2z}{15}=x+2$$

=> $$15x-100+2z=25x+30$$

=> $$2z=100+30=130$$

=> $$z=\frac{130}{2}=65$$

$$\therefore$$ Average age of the new members = 65

=> Ans - (C)

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