A contract on construction job specifies a penalty for delay in completion of the work beyond a certain date is 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 50 more than that of the preceding day. How much penalty should the contractor pay if he delays the work by 10 days?

1. Rs. 4950
2. Rs. 4250
3. Rs. 650
4. Rs. 3600

Penalty follows Arithmetic Progression (AP) with

First term, a = 200

Common difference, d = 50

Number of terms, n = 10

Sum of AP = n/2 [2a + (n-1)d]

Sum = 10/2 [2*200 +  (10-1)*50]

= 5 [400 + 450] = 4250

The correct option is B.