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 #602558 by </B><A HREF=/tutors/aboutme.mpl?userid=solver91311><B>solver91311(24713)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solver91311><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=solver91311><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=602558\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font face=\"Times New Roman\" size=\"+2\">\r<BR>\n" );
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document.write( "1.  Why is your answer 5.151 X 10^12 when the given significant digits are 4.151?\r<BR>\n" );
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document.write( "2a.  Why did you round the significant digits in your answer to one decimal place?  You carried three decimal places in your answer to #1.\r<BR>\n" );
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document.write( "2b.  You divided the significant digits of the answer to 2a by the significant digits of the answer to 1.  But the answer to 2a was a number times 10^11 and the answer to 1 was a number times 10^12.  Your answer to 2b is off by a factor of 10.\r<BR>\n" );
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document.write( "3b.  Move the decimal point on the significant digits on your answer to 3a 2 places to the left, making the number .0947 X 10^12.  Now you can divide .0947 by 4.151 since the powers of 10 are now equal.\r<BR>\n" );
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document.write( "3c.  <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \frac{0.2602\ +\ 0.0947}{4.151}\">\r<BR>\n" );
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document.write( "John<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE e^{i\pi}\ +\ 1\ =\ 0\"><BR>\n" );
document.write( "My calculator said it, I believe it, that settles it\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large \ \\r\"> </SPAN>\n" );
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