Question 57

The first and last terms of an arithmetic progression are -32 and 43. If the sum of the series is 88, then it has how many terms?

Solution

First term of AP, $$a=-32$$ and last term, $$l=43$$

Let there be $$n$$ terms

Sum of AP = $$\frac{n}{2}(a+l) = 88$$

=> $$\frac{n}{2}(-32+43)=88$$

=> $$\frac{11n}{2}=88$$

=> $$n=88 \times \frac{2}{11}$$

=> $$n=8 \times 2=16$$

=> Ans - (A)

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The first and last terms of an arithmetic progression are -32 and ­43. If the sum of the series is ­88, then it has how many terms?