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Question
Which term of the A.P. 3, 8, 13, ... is 248?
Solution
3, 8, 13...
Here, we have:
a = 3
\[d = \left( 8 - 3 \right) = 5\]
\[\text { Let } a_n = 248\]
\[ \Rightarrow a + \left( n - 1 \right)d = 248\]
\[ \Rightarrow 3 + \left( n - 1 \right)5 = 248\]
\[ \Rightarrow \left( n - 1 \right)5 = 245\]
\[ \Rightarrow n - 1 = 49\]
\[ \Rightarrow n = 50\]
Hence, 248 is the 50th term of the given A.P.
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