Question

Find the total cost of digging a well of depth 25m, after every meter

of digging, when it costs Rs.150 for the first meter and rises by Rs.50

for each subsequent meter​

Answer 1

Explanation:

here , use the property , sum of n terms of an A.P.

so,

S25 = 25/2 {150 + (25-1)50}

= 16875

therefore , the total cost of digging the well = Rs.16875