###
**The average of 8 numbers is 20. The average of first two numbers is $15 \Large\frac{1}{2}$ and that of the next three is $21 \Large\frac{1}{3}$. If the sixth number be less than the seventh and eighth numbers by 4 and 7 respectively, then the eight number is-
**

A. 18
B. 22
C. 25
D. 27
**Answer: Option C**

## Show Answer

Solution(By Apex Team)

Let the eight number be x
Then, sixth number = (x – 7)
Seventh number = (x – 7) + 4 = (x – 3)
So,
$\begin{aligned}&\Leftrightarrow\left(2\times15\frac{1}{2}\right)+\left(3\times21\frac{1}{2}\right)+(x-7)+(x-3)+x=8\times20\\
&\Leftrightarrow31+64+(3x-10)=160\\
&\Leftrightarrow3x=75\\
&\Leftrightarrow x=25\end{aligned}$

## Related Questions On Average

### Ajit has a certain average for 9 innings. In the tenth innings, he scores 100 runs thereby increasing his average19 people went to a hotel for combine dinner party 13 by 8 runs. His new average is:

A. 20B. 21

C. 28

D. 32

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C. 24

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### If the arithmetic mean of 0, 5, 4, 3 is a, that of -1, 0, 1, 5, 4, 3 is b and that of 5, 4, 3 is c, then the relation between a, b, and c is.

A. a = b = cB. a : b : c = 3 : 2 : 4

C. 4a = 5b = c

D. a + b + c = 12