Aptitude Discussion

Q. |
A club consists of members whose ages are in A.P. The common difference being 3 months. If the youngest member of the club is just 7 years old and the sum of the ages of all the members is 250, then number of members in the club are: |

✖ A. |
18 |

✖ B. |
20 |

✔ C. |
25 |

✖ D. |
24 |

**Solution:**

Option(**C**) is correct

Let $n$ be the number of members in the club

Then,

\(250=\dfrac{n}{2}[2\times 7+(n-1)\times \dfrac{3}{12}]\)

\(n=25\)

**Edit:** A typo in the solution has been corrected after it was pointed out by **Sravan Reddy.**

**Edit 2:** For a speed trickâ€‹ to solve the question, check comment by **Sravan Reddy.**

**Sravan Reddy**

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Thank you Sravan, for letting me know about the error, corrected it.

**Vikas**

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how does the 3/12 came ????

as the values are given in years and d=3 MONTHS (not years)....so 3/12 years

@Admin: Small correction in formula but calculation is correct - It should be (n-1) instead of (n+1) in the formula :)

Some speed trick to other friends: Write the equation and arrive at the answer by checking options.

Here $\dfrac{(n-1)*1}{4}$ should be a whole number - so option subtracted by 1 should be a multiple of 4.

So, 25 is the only odd number and is the answer.