Question 981619: this question is long but all of them have some type of connection. I have answer to the question that I could answer. I am asking for help.
1. According to the U.S. Energy Information Administration (www.eia.gov) the United States consumed 4.151 trillion kWh (kilowatt-hours) of electric energy in 2010. Write this number in correct scientific notation in terms of kWh.
My answer: 4.151 X 10^12
2. Of this electric energy, 260.2 billion kWh were produced by hydroelectric
sources (think water over dams – like Snoqualmie Falls) in 2010.
a) Write this number in correct scientific notation in terms of kWh.
My answer:2.602 x 10^11
b) What percent of the total US electric energy did hydroelectric sources
account for in 2010? (Round to the nearest 10th of a percent.)
My answer:6.3%
3. Additionally, 94.7 billion kWh were produced by wind power sources.
a) Write this number in correct scientific notation in terms of kWh.
My answer:9.47 x 10^10
b) What percent of the total US electric energy did wind power sources
account for in 2010? (Round to the nearest 10th of a percent.)
My answer:2.3%
c) What percent of the total US electric energy did hydro and wind power
sources account for in 2010 combined?
My answer: 8.6%
4. Scientific Notation is a good tool for multiplying and dividing, but not as good of a tool for adding and subtracting. If done correctly, your answers to #2a and 3a cannot easily be added.
a) What adjustment could be made to either 2a or 3a to allow you to add your values in scientific notation?
(Describe in words and demonstrate. Hint: think about “like terms”)
I am not sure what adjustments would be needed
b) Find the total combined amount of hydro and wind energy produced in 2010.
(Use your idea from part a) and write your answer in correct scientific notation in terms of kWh.)
I am not sure on how to set this problem up.
5. On average, an American household used 11,698 kWh in 2010.
a) How many American households could have been powered completely on hydro and wind power in 2010? (You may round to the nearest 10th of a million.)
I am not sure on how to set this problem up.
b) If there were 116.7 million households in 2010, your answer to part a) is what percentage of all American households? (Round to the nearest 10th of a percent.)
I am not sure on how to set this problem up.
c) If done correctly, your answer to 5b) doesn’t match your answer to 3c), though it seems it should. Why is this?
Answer by macston(5194)   (Show Source):
You can put this solution on YOUR website!
4. Scientific Notation is a good tool for multiplying and dividing, but not as good of a tool for adding and subtracting. If done correctly, your answers to #2a and 3a cannot easily be added.
a) What adjustment could be made to either 2a or 3a to allow you to add your values in scientific notation?
(Describe in words and demonstrate. Hint: think about “like terms”)
.
2a) 2.602 x 10^11
3a) 9.47 x 10^10
To be added, numbers must be of the same degree (the exponent of 10 must be the same) Convert 2.602 x 10^11 to 26.02 x 10^10, and:
(26.02 x 10^10)+(9.47 x 10^10)=(26.02+9.47)x10^10=35.49 x 10^10=3.59 x 10^11
.
b) Find the total combined amount of hydro and wind energy produced in 2010.
(Use your idea from part a) and write your answer in correct scientific notation in terms of kWh.)
.
This answer is given as example in part a above.
.
5. On average, an American household used 11,698 kWh in 2010.
a) How many American households could have been powered completely on hydro and wind power in 2010? (You may round to the nearest 10th of a million.)
.
Total kWh from hydro and wind=answer to 3b=3.59 x 10^11 kWh
divided by kWh/household (given)=1.1698 x 10^4 kWh:
.
Number of households=
.
b) If there were 116.7 million households in 2010, your answer to part a) is what percentage of all American households? (Round to the nearest 10th of a percent.)
.
((Answer to part a)/116.7 million)(100%)=percentage
.
c) If done correctly, your answer to 5b) doesn’t match your answer to 3c), though it seems it should. Why is this?
.
Households do not use 100% of power produced
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