document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1110094>Question 1110094</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the parents of a 9-year-old boy have agreed to deposit $10 in their son's bank account on his 10th birthday and to double the size of their deposit every year thereafter until his 18th birthday.<BR>\n" );
document.write( "a) how much will they have to deposit on his 18th birthday?<BR>\n" );
document.write( "b) how much will they have deposited by his 18th birthday? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #725084 by </B><A HREF=/tutors/aboutme.mpl?userid=addingup><B>addingup(3677)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=addingup><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=addingup><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=725084\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a = 10 and r = 2<BR>\n" );
document.write( "a_1 = a = 10 (his age, he is 10 at the time of the 1st deposit)<BR>\n" );
document.write( "a_2 = ra = 2 x 10 = 20 (he is 11)<BR>\n" );
document.write( "a_9 = r^(9-1) x a = 2^8 x 10 = 2,560 this is how much they deposited on his 18th b'day.<BR>\n" );
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document.write( "By his 18th b'day they will have deposited:<BR>\n" );
document.write( "S_9 = [a(r^9-1)]/r-1 = [10(2^9-1)]/2-1 = 10(512-1) = 5110 this is how much money the parents have deposited by his 18th b'day.\r<BR>\n" );
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