Question

A contract on construction job specifies a penalty for delay of completion beyond a certain date as follows $Rs200$ for the first day, $Rs250$ for the second day, $Rs300$ for the third day, etc. the penalty for each succeeding day being $Rs50$ more than for the preceding day. How much money the contractor has to pay as penalty, if he has delayed the work by $30$ days?

Answer 1

Penalty for delay in work

$200,250,300,350,.......$

for 30 days.

how much money?

$\to$ here, $a=200$

$d=50$

$n=30$

$S_n=\frac{n}{2}[2a+(n-1)d]$

$S_{30}=\frac{30}{2}[2\times 200+(30-1)50]$

$=15[400+29\times 50]$

$=15(400+1450)$

$=27,750$