Question

Medal
A space heater is used for 8 h. The heater uses 1600 W per hour. Electricity costs 12.9¢ per kilowatt-hour. Find the cost of using the electric heater. Round to the nearest cent.
$ ?

Answer 1

hello

Answer 2

that explains nothing

Answer 3

i dont think 12.8 * 8 is right

Answer 4

\[\frac{ 12.9 cents }{ 1000 W hr }*\frac{ 1600 W }{ 1 hr }* \frac{ 8 hr }{ 1 }\]

Answer 5

Keep track of your units, if the units do not come out right, in this case

Answer 6

\[\frac{ cost }{ hour }\]

Answer 7

so how would you multiply this

Answer 8

Just looking at the units, see that you result with Cents / Hour
W cancels, and hr cancels

Answer 9

\[\frac{ 12.9 * 1600* 8 }{ 1000 }\frac{ Cents }{ hr }\]

Answer 10

165120/1000

Answer 11

\[\frac{ 12.9 * 16 * 8 }{ 1 } \frac{ cents }{ hr }\]

Answer 12

1651.2/1

Answer 13

\[\frac{ 1651.2 cents }{ 1 hr } \]

Answer 14

Remember, the units are more important than the numbers, work through the units first to see if you get the correct resulting unit, in this case cents per hour

Answer 15

so are the units ok 1651.2 cents / 1 hr

Answer 16

m i right?

Answer 17

$1651.20

Answer 18

yes

Answer 19

ok thank you

Answer 20

It's no wonder you are confused. It's not watts per hour. It's watt times hours, or watt hours.

Whoever wrote the problem mislabeled it.