Question

Neela saves in a Mahila Bachat gat Rs. 2 on the first day of February, Rs. 4 on the second day, Rs. 6 on the third day and so on. What will be her saving in the month of February 2010?

• A. 786
• B. 812
• C. 892
• D. 788

Answer 1

The correct option is B 812

Since, $2010$ is not a leap year.
$\therefore$Total no. of days in the month of February $2010=28$
The savings done by Neela on each day is as follows $2,4,6,.......$
This sequenceform an A.P. with first term $a=2$ ,common difference $d=2$ and number of terms $n=28$.
Since, $S_n=\frac{n}{2}[2a+(n-1\left)d\right]$
$\Rightarrow S_{28}=\frac{28}{2}[2\times 2+(28-1\left)2\right]$
$\Rightarrow S_{28}=14[4+54]$
$\Rightarrow S_{28}=812$
$\therefore$Total savings for the month of February $\left(S_{28}\right)=Rs.812$