Average of 11 numbers is 10.9 If average of first six is 10.5 and average of last six is 11.4, middl

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The average of $11$ numbers is $10.9$ If the average of the first six is $10.5$ and the average of last six is $11.4,$ find the middle (sixth) number.

A

$11$

B

$10.6$

C

$11.5$

D

$10.45$

Solution

Total first $6$ number $=10.5 \times 6=63$

Total of last $6$ number $=11.4 \times 6=68.4$

Total of all $11$ number $=11 \times 10.9=119.9$

Sixth number $=63+68.4-119.9=11.5$

Hence the middle number is $=11.5$

Standard 13

Quantitative Aptitude

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