### Question

**The sum of the series 5 + 9 + 13 + … + 49 is:**

A. 351

B. 535

C. 435

D. 324

#### Answer: D. 324

**Solution:**

The given series is 5 + 9 + 13 + … + 49

which is an arithmetic progression with first term a = 5 and common difference d = 4.

Let’s say that the last term 49 is the nth term.

**∴ a + (n – 1)d = 49**

⇒ 5 + 4(n – 1) = 49

⇒ 4(n – 1) = 44

⇒ n = 12.

And, the sum of this AP is:

S12 = ((First term + Second term) / 2) * 12

s12 = ((5 + 49) / 2) * 12

= 54 * 6

**= 324.**

Hence, The sum of the series 5 + 9 + 13 + … + 49 is: **324.**

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