math
posted by shakira.shakira .
Insert 3 numbers between15 to 17 such that the terms from an Arithmetic progression

let the sequence be
15 , 15+d, 15+2d, 15+3d, and 17
then 17  (15+3d) = d
17  15  3d = d
4d = 2
d = 1/2 or .5
the inserted numbers are 15.5, 16, and 16.5