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Question
Which term of the AP 3,8, 13,18,…. Will be 55 more than its 20th term?
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Solution
Here, a = 3 and d = (8-3) = 5
The 20th term is given by
`T_20 = a + (20-1) d = a+ 19d = 3+ 19xx5 = 98`
∴ Required term = (98 + 55) = 153
Let this be the nth term.
Then Tn = 153
⇒ 3 +(n-1 ) × 5 = 153
⇒ 5n = 155
⇒ n= 31
Hence, the 31st term will be 55 more than 20th term.
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