# Homework Help: Electrical Usage Question

1. Nov 11, 2013

### mz19

A.) A 20-W compact fluorescent lamp replaces a 100-W incandescent bulb. How much energy does it save over its 10,000 hour lifetime?
B.) At $0.10 per kilowatt-hour, how much money does this save? My attempt at answering: Difference is wattage is 80-W, multiplied by 10,000 hours is 800,000 (not sure of the label here, is it Kilowatt hours?) saved. Is part B just multiplying the 800,000 (UNIT) saved times (0.10) to get$80,000 saved?

Thank you for your help!

2. Nov 12, 2013

### 256bits

UNIT: simple
80 watt times 10,000 hours = 80 times 10,000 x watt times hours = 80,000 watt-hours.

B:
How many kw-hours is 80, 000 watt-hours?

3. Nov 12, 2013

80000 watt hours is 80kwh. So multiply 80 kWh to get $8.00? 4. Nov 12, 2013 ### adjacent Ofcourse. 80 x 0.1 = 8 Or you can do this: 0.1$ --> 1Kwh
x --> 80

Just cross multiply, .

5. Nov 12, 2013

### xAxis

80x10000=800,000.
So you save 80 bucks

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted