Question

Find the sum of the ap 1/15,1/12,1/10 to 11 terms

Answer 1

Step-by-step explanation:

first term a=1/15

common difference d=1/12-1/15=1/60

sum of n term = n/2[2a+(n-1)d]

=11/2[2*1/15 +(11-1)*1/60]

= 11/2 [2/15 + 1/6]

=11/2* 3/10

=33/20

Hope it helps you

Answer 2

Answer:

Step-by-step explanation:

Given A.P:- 1/15,1/12,1/10,......S11

a=1/15;d=a2-a1= 1/12-1/15= 5-4/60=1/60

Sn=n/2(2a+(n-1)d)

S11=11/2(2*1/15+(11-1)*1/60)

11/2(2/15+10/60)

11/2(4*2+10*1/60)

11/2(8+10/60)

=11/2*18/60=33/20