Question 10

What is the average of first 11 multiples of 11?

Solution

First eleven multiples of 11 will form an arithmetic progression : 11,22,33,.......,121

First term, $$a=11$$ and common difference, $$d=11$$

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

=> $$S_{11}=\frac{11}{2}(11+121)$$

= $$11\times66$$

Now, average of 11 terms = $$\frac{11\times66}{11}=66$$

=> Ans - (D)

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