Q11 of 102 Page 429

The first and last terms of an AP are 1 and 11 respectively. If the sum of its terms is 36, find the number of terms.

Given: the sum of its terms is 36, the first and last terms of an AP are 1 and 11.


To find: the number of terms


Sum of AP using first and last terms is given by



36 × 2 = n (1 + 11)


n = 6


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