document.write( "Question 788593: Kendall is planning to buy a laptop for 1200 each month she doubles the amount she saved the previous month.If she saves $20 the first month in how many months will Kendall have enough money to buy the laptop
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Algebra.Com's Answer #478555 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Amount saved each month:
\n" ); document.write( "1st month: 20
\n" ); document.write( "2nd month: 2*20
\n" ); document.write( "3rd month: 4*20
\n" ); document.write( "4th month: 8*20
\n" ); document.write( "etc.
\n" ); document.write( "Summing up the amounts saved:
\n" ); document.write( " $\"+20+%2B+2%2A20++4%2A20+%2B+8%2A20+\"$ etc,.
\n" ); document.write( " $\"+20%2A%28+1+%2B+2+%2B+4+%2B+8+%29+\"$ etc.
\n" ); document.write( " $\"+20%2A%28+2%5En+-+1+%29+\"$
\n" ); document.write( "where $\"+n+\"$ is the number of months
\n" ); document.write( "given:
\n" ); document.write( " $\"+20%2A%28+2%5En+-+1+%29+=+1200+\"$
\n" ); document.write( " $\"+2%5En+-+1+=+60+\"$
\n" ); document.write( " $\"+2%5En+=+61+\"$
\n" ); document.write( "Take log base 10 of both sides
\n" ); document.write( " $\"+n%2Alog%282%29++=+log%2861%29+\"$
\n" ); document.write( " $\"+.301n+=+1.785+\"$
\n" ); document.write( " $\"+n+=+5.931+\"$
\n" ); document.write( "She will have enough money in about 6 months
\n" ); document.write( "check:
\n" ); document.write( " $\"+20%2A%28+1+%2B+2+%2B+4+%2B+8+%2B+16+%2B+32+%29+=+20%2A63+\"$
\n" ); document.write( " $\"+20%2A63+=+1260+\"$
\n" ); document.write( "At the end of only 5 months, she has:
\n" ); document.write( " $\"+20%2A%28+1+%2B+2+%2B+4+%2B+8+%2B+16+%29+=+20%2A31+\"$
\n" ); document.write( " $\"+20%2A31+=+620+\"$
\n" ); document.write( "OK
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