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Energy: 0.48
Cost: 0.27
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
81% (03:00) correct
19%
(03:26)
wrong
based on 365
sessions
History
Date
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Not Attempted Yet
For Christmas, a family decorated their home with Christmas lights. They installed two types of lights: string lights and icicle lights. During Christmas Day: • Each string light has a power of 0.6 watts and runs for 10 hours.
• Each icicle light has a power of 2 watts and runs for 12 hours.
• The family uses 250 string lights and 20 icicle lights.
• The total electricity rate is $0.18 per kilowatt-hour (1 kilowatt = 1000 watts).
Based on the information provided, select for Energy the total energy consumption (in kilowatt-hours) of all icicle lights over their full 12-hour runtime on Christmas Day and select for Cost the total electricity cost (in dollars) of running all string lights for their full 10-hour runtime on Christmas Day.
• Each icicle light has a power of 2 watts and runs for 12 hours.
• The family uses 250 string lights and 20 icicle lights.
• The total electricity rate is $0.18 per kilowatt-hour (1 kilowatt = 1000 watts).
Based on the information provided, select for Energy the total energy consumption (in kilowatt-hours) of all icicle lights over their full 12-hour runtime on Christmas Day and select for Cost the total electricity cost (in dollars) of running all string lights for their full 10-hour runtime on Christmas Day.
| Energy | Cost | |
| 0.24 | ||
| 0.27 | ||
| 0.36 | ||
| 0.48 | ||
| 0.50 | ||
| 0.65 |
ShowHide Answer
Official Answer
Energy: 0.48
Cost: 0.27
08 Apr 2025, 08:08
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Official Solution:
Energy (icicle lights):
Each icicle light: 2 * 12 = 24 watt-hours = 0.024 kWh
20 icicle lights: 20 * 0.024 = 0.48 kWh
Cost (string lights):
Each string light: 0.6 * 10 = 6 watt-hours = 0.006 kWh
250 string lights: 250 * 0.006 = 1.5 kWh
Cost: 1.5 * 0.18 = 0.27 dollars
Correct answer:
Energy "0.48"
Cost "0.27"
Bunuel
Energy (icicle lights):
Each icicle light: 2 * 12 = 24 watt-hours = 0.024 kWh
20 icicle lights: 20 * 0.024 = 0.48 kWh
Cost (string lights):
Each string light: 0.6 * 10 = 6 watt-hours = 0.006 kWh
250 string lights: 250 * 0.006 = 1.5 kWh
Cost: 1.5 * 0.18 = 0.27 dollars
Correct answer:
Energy "0.48"
Cost "0.27"
General Discussion
26 Dec 2024, 07:00
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1. Each icicle light uses \(2 \ watts * 12 \ hours = 24 Wh = 0.024 kWh\). Since there are 20 of them, then together they use up \(0.024 kWh * 20 = 0.48 kWh\).
2. Let’s first find the total amount of energy consumed by the string lights and then we can determine how much that energy would cost. Each string light uses \(0.6 \ watts * 10 \ hours = 6 Wh = 0.006 kWh\). Since there are 250 of them, then together they use up \(0.006 kWh * 250 = 1.5 kWh\). The cost per kWh is $0.18, so the total cost will be \(\$0.18 * 1.5 = \$0.27\).
3. Our answer will be: Energy - 0.48 and Cost - 0.27.
2. Let’s first find the total amount of energy consumed by the string lights and then we can determine how much that energy would cost. Each string light uses \(0.6 \ watts * 10 \ hours = 6 Wh = 0.006 kWh\). Since there are 250 of them, then together they use up \(0.006 kWh * 250 = 1.5 kWh\). The cost per kWh is $0.18, so the total cost will be \(\$0.18 * 1.5 = \$0.27\).
3. Our answer will be: Energy - 0.48 and Cost - 0.27.
