Question

What two numbers should be placed in the blanks below so that the difference between the

consecutive numbers is the same?
13,_,_,34

Answer 1

20, 27

Explanation:

The difference 34-13 = 21 must be divided into three equal parts. Each is 21/3 = 7.

The numbers are 13+7 = 20, 20+7 = 27. As a check, 27 +7 = 34

The missing numbers are 20 and 27.

Answer 2

20,27

Explanation:

let 13,a,b,34 be consecutive numbers.

a=13

l=34

n=4

l=a+(n-1)d

34=13+(4-1)d

34-13=3d

21=3d

d=21/3=7

a=13+7=20

b=20+7=27