Average of 13 results is 60 . If average of first 7 results is 59 and that of last 7 results is 61,

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The average of $13$ results is $60 .$ If the average of first $7$ results is $59$ and that of last $7$ results is $61,$ what will be the seventh result $?$

A

$90$

B

$50$

C

$75$

D

$60$

Solution

Sum of the first $13$ Results $=13 \times 60=780$

Sum of the first $7$ Results $=59 \times 7=413$

Sum of the last $7$ Results $=7 \times 61=427$

$7 th$ Result $=$ Sum of first $7$ Results $+$ sum of last $7$ Results – sum

of $13$ Results $=413+427-780$

$=840-780=60$

Standard 13

Quantitative Aptitude

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