Let the four numbers be (a – 3d), (a – d), (a + d) and (a + 3d)
a – 3d + a – d + a + d + a + 3d = 50
4a = 50
a = \(\frac{25}{2}\)
According to question,
(a + 3d) = 4(a – 3d)
a + 3d = 4a – 12d
3a = 15d
5d = \(\frac{25}{2}\)
d = \(\frac{5}{2}\)
Therefore,