A hole of up to 60 meters in depth needs to be bored for oil exploration purposes. The cost of boring is £50 for drilling the first meter with an increase in cost of £2 per meter for all succeeding meter.

Find number of terms of the series  5, 8, 11,  ... of which the sum is 1025.

The 1^st , 12^th  and last term of an arithmetic progression are 4, 31.5 and 376.5 respectively. Find the common difference.

Recurring decimal can be written as 0.13 + 0.0013 +0.000013+ ...

Find the value of  0.\ \dot1\ \dot3

Find sum of first nine terms of series: 0.25, 0.75, 2.25, ...