Question

7. The first term of an AP is 5, the last term is 45 and the sum is 400. Find the number of terms.

Answer 1

Answer:

16

Step-by-step explanation:

s = 400

l = 45

a = 5

now

s = n/2 × (a +l)

400 = n/2 (50)

400/50 = n/2

n/2 = 8

n = 16

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