Question

The mean of the first ten even natural numbers is
A.10
B.11
C.12
D.13

Answer 1

Hint: To find the mean of the first 10 even natural numbers, we will first note down the first 10 even natural numbers, then we will add all these numbers and get a sum. And then finally to get their mean will divide their summation by the total numbers added, which in this case will be 10 numbers.

Complete step-by-step answer:
The first 10 even natural numbers are 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20.
Now, their summation will be given as \[2 + 4 + 6 + 8 + 10 + {\text{1}}2 + 14 + 16 + 18 + 20 = 110\].
As we want to find the mean of the first 10 even natural numbers, we will divide their summation value by the total number of values, which is 10.
Thus, on dividing the summation value by 10 we get, \[\dfrac{{110}}{{10}} = 11\].
Thus, the mean of the first 10 even natural numbers will be 11.
Hence, option (B) is the correct option.

Note: Here, we should make sure that we don’t use the formula to find the sum of first \[n\] natural numbers, because here we are not considering all the natural numbers but only the even numbers. Also, while adding the numbers we notice that 2 of the numbers will add up to give 20 as their sum. For example, 2 and 18, 4 and 16, 6 and 14, 8 and 12. Forming such pairs can help in adding more quickly and thus saving the time for calculations.