Question

Out of 9 persons, 8 persons spent Rs. 30 on each of their meals. The ninth one spends Rs. 20 more than the average expenditure of all the nine. The total money spent by all of them was

• A. Rs. $260$
• B. Rs. $290$
• C. Rs. $292.50$
• D. Rs. $400.50$

Answer 1

Answer: (C)

Rs. $292.50$

Given that eight members spent Rs. $30$ each.

Let the average expenditure of all the nine be $\overline{x}$

Given that ninth member spent Rs. $20$ more than the $\overline{x}$

Therefore, the amount spent by the ninth member is $\overline{x}+20$

Hence, $\overline{x}=\frac{(30\times 8)+\overline{x}+20}{9}$

$⟹9\overline{x}=240+\overline{x}+20$

$⟹8\overline{x}=260$

$⟹\overline{x}=32.5$

Total money spent by them is $(30\times 8)+32.5+20=292.50$