Question

If 5th term of GP is 32 and common ratio is 2 then find the value of S15

Answer 1

given
a5=32
d=2
a5=a+4d
32=a+4×2
32=a+8
32-8=a
a=24
sn=n/2 (2a+n-1×d)
s15=15/2 (2×24+15-1×2)
s15=15/2 (48+15-2)
s15=15/2×61
s15=457.5
HOPE IT HELPS