Average of 17 numbers is 10.9 If average of first nine numbers is 10.5 and that of last 9 numbers is

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4.Average

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The average of $17$ numbers is $10.9 $ If the average of first nine numbers is $10.5$ and that of the last $9$ numbers is $11.4,$ the middle number is

A

$11.8$

B

$11.4$

C

$10.9$

D

$11.7$

Solution

Sum of first nine numbers $+$ sum of last nine numbers $=10.5 \times 9+11.4 \times 9=21.9 \times 9=197.1$

Hence, the middle number

$=197.1-17 \times 10.9$

$=197.1-185.3=11.8$

Standard 13

Quantitative Aptitude

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