Grade level: 4 – 5th grades
Skills: Multiply Decimals
Related environmental issues: Energy
Area level: State
Alayna lives in Pennsylvania. The electricity price in where she lives was 14.4 cents for one kilowatt hour (kWh) in both November and December 2015.
1.Alayna’s family uses 910 kWh per month, which is very close to the average in the United States. How many dollars did Alayna’s family pay for electricity in November?
2.The average electricity price in the United States was 12.7 cents per kWh in November. How many more dollars did Alayna’s family pay for electricity than the average for 910 kWh?
3.Alayna learned that she can save electricity by adjusting home’s thermostat to 68 °F during winter and she followed the advice. In December, she found that her family could save electricity by 90 kWh. How many dollars did her family save because of the Alayna’s effort?
4.They decided to keep their thermostat at 68 °F during winter and at 78 °F during summer, and her family could save 90 kWh each month. How many dollars can Alayna’s family save in a year?
Source: US Energy Information Administration & EIA
1.$ 131.04 (910 x 14.4 = 13,104) Between 2010 and 2011
2.$15.47 (910 x 12.7 = 11,557 cents ; $131.04 – $115.57 = $15.47
3.$12.96 (90 x 14.4 = 1,296 cents)
4.$ 155.52 (12.96 x 12 = 155.52)