Question

sum of the terms of an AP having 25 terms is 400.find the 10 th term of an AP

Answer 1

Solution:

It is given that,

number of terms in A.P(n) = 25

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Sum of n terms

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

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S25 =400

=> (25/2)[2a+(25-1)d]=400

=> 2a+24d = (400×2)/25

=> 2a+24d= 16×2

Divide each term by 2 , we get

a + 12d = 16

=> a+(13-1)d = 16

Therefore,

13th term in given A.P is 16

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