Question

Find the three arithmetic means in this sequence. 21,_,_,_,45

Answer 1

It's nr 6
21,27,33,39,45
21+6=27
27+6=33
33+6=39
39+6=45

Answer 2

21, 27, 33, 39, 45

Explanation:

let find the difference to get the three arithmetic means

a = 21

5th term = 45

AP = a + (n - 1)d

45 = 21 + (5 - 1 )d

45 = 21 + 4d

45 - 21 = 4d

4d = 24

divide both sides by 4

d = 24/4

d = 6

Find the 2nd, 3rd and 4th term

a + d

2nd term = 21 + 6 = 27

3rd term = 27 + 6 = 33

4th term = 33 + 6 = 39