Question

How much does it cost to run a 15 A dryer plugged into a 240 V outlet for 55 minutes, seven times a month?

Answer 1

Write the data down:

I = 15 A

V = 240 V

t = 55 minutes

7x a month

Calculate the electric power output of the dryer:

P = I x V

P = 15 x 240

P = 3,600 W

Convert 55 minutes in seconds:

55 minutes x 60 seconds = 3,300 seconds

Since the dryer is used 7 times a month the total time it will be on is:

T = 7 x 3,300

T = 23,100 s

So the energy cost will be:

E = P x T

E = 3,600 X (23,100)

E = 83,160,000 J

Or in scientific notation we have:

$E=8.316\times10^7J$