Question

What is the average of all numbers between 8 and 74 which are divisible by 7?

Answer 1

(14+21+28+35+42+49+56+63+70)/9
=378/9
=42

Answer 2

Answer:

The correct answer is 42

Step-by-step explanation:

Numbers between 8 to 74 which are divisible by 7 is the 7 table sequence from 14 to 70 :  14 21 28 35 42 49 56 63 70.

The numbers are in A.P. with common difference(d) = 7.

$\text{Sum of n terms in an A.P. is given by : }\frac{n}{2}\cdot (2\cdot a+(n-1)\cdot d)$

Now, n is no. of terms = 9 ,                                                                           a is the first term = 14 and d is common difference = 7

$\textbf{Sum of terms is = }\frac{9}{2}\cdot(2\times 14+8\times 7)\\\\\textbf{Sum = } 4.5\times 84 =378\\\\\textbf{Average = }\frac{\text{Sum of all numbers}}{\text{Total no. of numbers}}\\\\\textbf{Average = }\frac{378}{9} =42$