Question

An electricity supply company charges ₹8.50 per unit for first 'p' units, and then ₹10 per unit. How much money does a man needs to pay who used 'r' units of electricity, where p < r ?

• A. 8.50 $\times$ r
• B. 10 $\times$ r
• C. 8.50 $\times$ p + 10 $\times$ r
• D. 8.50 $\times$ p + 10 $\times$ (r - p)

Answer 1

The correct option is D 8.50 $\times$ p + 10 $\times$ (r - p)

Amount of electricity used by the man = 'r' units
We are given that p < r.
For the first 'p' units, the man will be charged ₹8.50 per unit, and for the remaining (r - p) units he will be charged ₹10 per unit.
Therefore, the total amount of money that the man needs to pay
= 8.50 $\times$ p + 10 $\times$ (r - p)