Question

Write the arithmetic sequence that has four arithmetic means between -20 and 20.

Answer 1

let the terms be

a , a+d, a+2d, a+3d, a+4d a + 5d

so a = -20
and a + 5d = 20

-20 + 5d = 20
5d = 40 so
d = 8

-20,-12,-4,4,12,20 is the required sequence.