Question

If average of four numbers is 20 and average of their squares is 500, then average of their products taken two at a time is​

Answer 1

Let the four consecutive even numbers be x-3, x-1, x+1, x+3 respectively.

As their average is 20, we can write

[(x-3)+(x-1)+(x+1)+(x+3)] / 4 =20

(4x)/4 =20

x =20

The largest number will be = x+3 = 20+3 =23

Sum of the squares of number is = 500

The sum of the term is =20

(x-3)+(x-1)+(x+1)+(x+3) =20

4x =20

Hence a=5