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- Standard 13
- Quantitative Aptitude
4.Average
easy
The average age of a group of persons going for a picnic is $16.75 \,years.$ $20$ new persons with an average age of $13.25 \,years$ join the group on the spot due to which the average of the group becomes $15\, years.$ Find the number of persons initially going for the picnic $?$
A
$24$
B
$20$
C
$15$
D
$18$
Solution
Let the person initially going for picnic is $x$
$16.75 \times x+20 \times 13.25=15(x+20)$
$1.75 x=15 \times 20-20 \times 13.25$
$1.75 x=35 \Rightarrow x=20$
Standard 13
Quantitative Aptitude