Question

Use Gauss method to find which term of the A.P. 1, 3, 5, 7 ......... is 153?

• A. 77
• B. 76
• C. 75
• D. 74

Answer 1

The correct option is A 77

Gauss formula for nth term of the A.P. is $a_n=a+(n-1)d$
Given; $a=1,d=2,a_n=154$
$153=1+(n-1)2$
$153-1=2n-2$
$153-1+2=2n$
$n=\frac{154}{2}=77$