document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1190016>Question 1190016</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The worldwide number​ (in millions) of a particular phone sold can be approximated by the function f(x)=-871+398lnx, where x=11 corresponds to 2011.\r<BR>\n" );
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document.write( "​(a) What was the number of worldwide sales for the particular phone in ​2015?<BR>\n" );
document.write( "​(b) If the model continues to be​ accurate, what was the first full year in which the particular phone sales exceed 254 ​million?\r<BR>\n" );
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document.write( "PLEASE ANSWER A & B </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #821567 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=821567\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> f(4-2015)=-871+398 ln 15=206.80 million phones<BR>\n" );
document.write( "254=-871+398 lnx. Isolate the ln x<BR>\n" );
document.write( "1125=398 ln x<BR>\n" );
document.write( "ln x=2.8266. Without rounding, raise that to the e power<BR>\n" );
document.write( "x=16.889 or 17 years or 2017<BR>\n" );
document.write( "check<BR>\n" );
document.write( "-871+398 ln 17=256.61M which is just greater than 254M. </SPAN>\n" );
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