1.

Find the average of first 21 multiples of 21?1). 2312). 2413). 214). 11

Answer»

First 21 multiples of 21 are - 21, 42, 63 …. 441

AVERAGE of odd number of consecutive terms is always equal to the value of the middle term

⇒ If there are N number of consecutive terms,

⇒ Average = [(n + 1)/2]th term

⇒ Here n = 21

∴ Average = [(21 + 1)/2]th term = 11th term

⇒ 11th term will be 11th multiple of 21 = 21 × 11 = 231


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