A) 20
B) 25
C) 21.6
D) 25.3
Correct Answer: B
Solution :
\[\therefore \] Required Average age\[=\frac{96}{3}=32\,\,\text{yr}\] |
Sum of the eighth numbers \[=20\times 8=160\] |
Sum of the first two numbers = 31 |
Sum of the next three numbers \[=\frac{64}{3}\times 3=64\] |
Let the sixth number \[=x\] |
\[\therefore \] Seventh number \[=x+4\] |
and eighth number \[=x+7\] |
\[\therefore \] \[31+64+x+x+4+x+7=160\] |
\[\Rightarrow \] \[3x+106=160\] |
\[\Rightarrow \] \[3x=160-106=54\] |
\[\Rightarrow \] \[x=\frac{54}{3}=18\] |
\[\therefore \] Eighth number \[=x+7=18+7=25\] |
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