Question

a=1/15 d=1/60 n=11 find S11​

Answer 1

Answer:

Step-by-step explanation:

a = 1/15,  

d = 1/12 - 1/15 = (5 - 4)/60

= 1/60

We know, sum of n terms  

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

Then, sum of 11 terms of given AP

S11 = 11/2[2*1/15 + 10*1/60]

= 11/2[2/15 + 10/60]

= 11/2[(8 + 10)/60]

= 11/2(18/60)

= 33/20

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