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The 4th term of an A.P. is 13 while the 10th term is 31. Find…

The 4th term of an A.P. is 13 while the 10th term is 31. Find the 24th term.
  • A.
    89
  • B.
    75
  • C.
    73
  • D.
    69
Correct Answer: Option C
Explanation

a + 3d = 13 ………. (1)
a + 9d = 31 ………. (2)
(2) – (1): 6d = 18
d = 18/6 = 3
From (1), a + 3(3) = 13
a + 9 = 13
a = 13 – 9 = 4
Hence,
T24 = a + 23d
T24 = 4 + 23(3)
T24 = 4 + 69
T24 = 73

There is an explanation video available below.

Explanation Video

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