Question

Fourth term of an arithmatic progression is 11. The sum of the fifth and seventh term of the arithmatic progression is 24. Find the common difference

Answer 1

a4=11
a5+a7=24
d=?
a+3d=11 (1)
a+4d + a+6d=24
2a+10d=24
a+5d=12 (2)
sub equation 2 and 1 we get
-2d = -1
d= 1/2

Answer 2

let first term be =a and common difference =d then fourth term = a+3d
fifth term=a+4d
seventh term= a+6d