A contract on construction job specifies a penalty for delay of completion beyond a certain date as follows: Rs 200 for the first day, Rs 250 for the second day Rs 300 for the third day, etc., the penalty for each succeeding day being Rs 50 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?

Explanation

To find the total penalty the contractor has to pay for a delay of 30 days, we can follow these steps:

### Step 1: Identify the first term and common difference
The penalty for the first day is Rs. 200. The penalty increases by Rs. 50 each day. Therefore:
- First term (a) = Rs. 200
- Common difference (d) = Rs. 50

### Step 2: Write the formula for the sum of the first n terms of an arithmetic progression (AP)
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