Question

The first and last terms of an AP are 5 and 45 respectively. If the sum of all its terms is 400, find the common difference and the number of terms.

Answer 1

Suppose there are n term in the AP.

Here, a = 5, l = 45 and S_n = 400

Thus, there are 16 terms in the AP. 

Let d be the common difference of the AP.

Hence, the common difference of the AP is \(\frac{8}{3}.\)