The first and the last terms of an A.P. are 5 and 45 respectively. If – InterviewSolution

InterviewSolution

1.	The first and the last terms of an A.P. are 5 and 45 respectively. If thesum of all its terms is 400, find its common difference.
Answer» Correct Answer - `d = (8)/(3)` and n = 16 `S_(n) =(n)/(2) (a+l) rArr (n)/(2) (5+45) = 400 rArr n = 16.` `S_(16) = 45 rArr a + 15d = 45 rArr 5 + 15d = 45 rArr d = (8)/(3)`

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