Question

Sum of all two digit numbers which when divided by 4 yield unity as remainder is

• A. 1200
• B. 1210
• C. 1250
• D. None of these

Answer 1

The correct option is B

1210

The given series is 13, 17, 21, .... 97

$a_1=13,a_2=17,a_n=97$

$d=a_2-a_1=7-3=4$

$a_n=97$

$\Rightarrow a+(n-1)d=97$

$\Rightarrow 13+(n-1)d=97$

$\Rightarrow n=22$

Sum of the above series:

$S_{22}=\frac{22}{2}\{2\times 13+(22-1\left)4\right\}$

= 11 {26 + 84}

= 1210