Question

The first and last term of an ap are 5 and 45 respectively if the sum of all its terms is 400 find in common difference

Answer 1

a= 5 ,an=45
Sn=n/2 (a+l)
400=n/2 (5+45)
400=n/2×50
400=25n
n=16
an=a+(n-1)d
45=5+(16-1)d
45-5=(16-1)d
40=(16-1)d
40=15d
d=8/3

Answer 2

hope this answer will help you.