document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=981583>Question 981583</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I know this is a long question. I have done the best that I could do. I am having trouble figuring out the percentages. All of the question have something in common with each other.\r<BR>\n" );
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document.write( "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.<BR>\n" );
document.write( "My answer:5.151 X 10^12\r<BR>\n" );
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document.write( "2. Of this electric energy, 260.2 billion kWh were produced by hydroelectric<BR>\n" );
document.write( "sources (think water over dams – like Snoqualmie Falls) in 2010.\r<BR>\n" );
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document.write( "a) Write this number in correct scientific notation in terms of kWh.<BR>\n" );
document.write( "my answer:2.6 X 10^11\r<BR>\n" );
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document.write( "b) What percent of the total US electric energy did hydroelectric sources<BR>\n" );
document.write( "account for in 2010? (Round to the nearest 10th of a percent.)<BR>\n" );
document.write( "My answer: 62%\r<BR>\n" );
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document.write( "3. Additionally, 94.7 billion kWh were produced by wind power sources.<BR>\n" );
document.write( "a) Write this number in correct scientific notation in terms of kWh.<BR>\n" );
document.write( "My answer: 9.47 X 10^10\r<BR>\n" );
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document.write( "b) What percent of the total US electric energy did wind power sources<BR>\n" );
document.write( "account for in 2010? (Round to the nearest 10th of a percent.)<BR>\n" );
document.write( "I can not figure out the percentage.\r<BR>\n" );
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document.write( "c) What percent of the total US electric energy did hydro and wind power<BR>\n" );
document.write( "sources account for in 2010 combined?<BR>\n" );
document.write( "I can not figure out the percentage.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #602559 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=602559\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The first is 4.151 x 10^12<BR>\n" );
document.write( "The second is correct.<BR>\n" );
document.write( "The third is the ratio of 2.6 X10 ^11/4.51x10^12= 26X10^10/4.151x10^12 = 6.263x10^-2<BR>\n" );
document.write( "That is 0.06263= 6.3%<BR>\n" );
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document.write( "The fourth is <BR>\n" );
document.write( "9.47 x 10^10/4.151 x 10^12=2.28 x 10^-2=0.0228 or 2.3%.<BR>\n" );
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document.write( "The last is 3.549X10^11/4.151 x10^12, and it should be the sum of those two percentages (maybe slightly different because of rounding).<BR>\n" );
document.write( "0.8550^10-1=8.550X10^-2, the latter being scientific notation.\r<BR>\n" );
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document.write( "That is 0.0855=8.6%.\r<BR>\n" );
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document.write( "Notice how 0.1 x 10^2=1 x 10^1<BR>\n" );
document.write( "I multiply 0.1 x 10 and divide 10^2 by 10, which doesn't change anything.\r<BR>\n" );
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