Sequence And Series Question 18
If the $ 9^{th} $ term of an A.P. is 35 and the $ 15^{th} $ term is 75, then its $ 20^{th} $ term will be
[RPET 1989]
Options:
78
79
80
81
Show Answer
Answer:
Correct Answer: B
Solution:
$ T_9=a+8d=35 $ and $ T_{19}=a+18d=75 $ Solving the equations, we get $ d=4 $ and $ a=3 $ Hence $ 20^{th} $ term of A.P. $ a+19d=3+19\times 4=79 $ .
BETA
