Question

A 1200 watt motor has to be operated 12 hours day. How much will it cost at the rate of Rs. 7.50/unit in 12 days?
O Rs. 108
O Rs.1926
O Rs. 1296
O Rs.1080​

Answer 1

Answer:

unit in a day 1.2kWx 12hrs = 14.4 unit

unit in 12 days = 172.8 unit

cost- 172.8x 7.50 = rs 1296

Answer 2

Answer:

It will cost Rs.1080 in 12 days.

Explanation:

The total cost of energy used is given as,

$E=P\times t$        (1)

Where,

E=total cost of energy used in rupees

P=power consumed by the motor

t=total time taken

From the question we have,

P=1200 watt

t=12 days=12×12=144hour=144×3600 seconds

Cost per unit of energy =Rs.7.50=$\frac{7.50}{3600}$/J

By substituting the required values in equation (1) we get;

$E=144\times 3600\times \frac{7.50}{3600}$

$E=Rs.1080$

Hence, it will cost Rs.1080 in 12 days.