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The first term of an AP is 7, the last term 77 and the sum is 380. Find the common difference in the series

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The common difference in the arithmetic progression is approximately 8.70.

How to solve

Given:

First term (a) = 7

Last term (l) = 77

Sum of the AP (S) = 380

Formula for the sum of an AP:

S = n/2 * (a + l)

We would substitute the values here:

380 = n/2 * (7 + 77)

380 = n/2 * 84

760 = n

n = 9.0476

The formula for the common difference (d):

d = (l - a) / (n - 1)

We would substitute the valuesa

d = (77 - 7) / (9.0476 - 1)

d = 70 / 8.0476

d ≈ 8.70 (rounded to two decimal places)

Therefore, the common difference in the arithmetic progression is approximately 8.70.

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