A Business Loss

My friend, Praveen, was inclined towards business and became a painting contractor. He started well and completed several projects satisfactorily and ahead of schedule.

But, there was one contract in which he suffered a loss. Praveen bagged a good house painting contract. He started work and completed 75 percent of the painting contract when all his painters fell ill; he had to stop work.

Under the contract, Praveen had to complete the work by a fixed date. If he failed to complete the work by that date, he would have to pay a fine. The fine was as follows: He had to pay a penalty of Rs. 500 for the first day's delay. For each succeeding day, the fine was Rs. 50 more than the previous day.

So, for instance, if he delayed the work by two days, then Praveen would have to pay 500 + 550 = 1050 as the penalty; if he were behind schedule by three days, the total fine would be 500 + 550 + 600 = 1650; if Praveen were late by four days, he would have to pay 500 + 550 + 600 + 650 = 2300.

Praveen's painters took nearly three weeks to recover, after which they joined work and completed the project. But there was a delay of 30 days. Praveen had to pay a hefty penalty. How much did he have to pay?

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