Question

Which term of the sequence $72,70,68,66,...$ is $40$ ?

• A. 12
• B. 15
• C. 17
• D. 19

Answer 1

Answer: (C)

17

The given sequence is an A.P. with first term $a=72$ and common difference $d=-2$. Let its nth term be 40.

$a_n=40$

$a+(n-1)d=40$

$72+(n-1)(-2)=40$

$72-2n+2=40$

$2n=34$

$n=17$

Hence, 17th term of the sequence is 40.