A) 10th
B) 12th
C) 14th
D) 16th
Correct Answer: D
Solution :
(d): Let nth term be 78. Given, 3, 8, 13, 18........are in AP. First term, a = 3, common difference, d = 8 ? 3 = 5 \[\because \] nth term \[{{a}_{n}}=78\] \[\therefore \] \[a+(n-1)d=78\Rightarrow 3+(n-1)5=78\] \[\Rightarrow \]\[(n-1)5=78-3\Rightarrow 5(n-1)=75\] \[\Rightarrow \]\[n-1=15\Rightarrow n=15+1\Rightarrow n=16\] Thus, 78 term is 16th.You need to login to perform this action.
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