Progression Practice Test 1

Question : 4 of 23

Marks: +1, -0

Find the sum of the series 5, 11, 17, 23 .... 65.

Solution:

The terms of the given series from an AP with the first term is a = 5 and common difference is d = 6. Let the number of terms be n.

∴t_n=65

⇒a+(n-1)d=65

⇒5+(n-1)6=65

⇒n=11

∴ Required sum

=S_11=11/2(5+65)=385

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