The 4th term of an A.P. is 13 while the 10th term is 31. Find the 24th term.
- 89
- 75
-
73
- 69
The correct answer is: 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
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