| 3 yr before, the average age of a family of 5 members was 17 yr. Due to birth of a now child, the average age is same today. The present age of child is [SSC (FCI) 2012] |
A) \[1\,\,yr\]
B) \[3\,\,yr\]
C) \[2\frac{1}{2}\,\,yr\]
D) \[2\,\,yr\]
Correct Answer: D
Solution :
| 3 yr before, |
| Total age of 5 members \[=17\times 5=85\,\,yr.\] |
| \[\therefore \]The present age of all members of family |
| \[=85+3\times 5=100\,\,yr.\] |
| Let the age of child be x yr. |
| \[\therefore \]Present average age of family including the child |
| \[=\frac{100+x}{6}\] |
| \[\Rightarrow \] \[17=\frac{100+x}{6}\] |
| \[\therefore \] \[x=102-10=2\,\,yr\] |
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