Question

Find n, if the sum of n items of A.P 48, 45, 42, ....... is 408 *
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n = 16 or n = 15

n = 15 or n = 17

n = 16 or n = 17

n = 17 or n = 18

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Answer 1

Answer:

here a(first term of AP)=48

diffrence =3

by using formula an=a+(n-1)d

=408=48+(n-1)3

=408-48=3n-1

=360/3=n-1

=120+1

=121

THEREFORE n = 16 or n = 15 IS CORRECT ☺

Step-by-step explanation:

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