document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1148014>Question 1148014</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The radioactive tracer ⁵¹Cr can be used to locate the position of the placenta in a pregnant woman. Often the tracer must be ordered from a medical laboratory. If A₀ units (microcuries) are shipped, then because of the radioactive decay, the number of units A(t) present after t days is given by <BR>\n" );
document.write( "A(t) = A₀e^(−0.0249t)\r<BR>\n" );
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document.write( "a) If 40 units are shipped and it takes 2 days for the tracer to arrive, approximately how many units will be available for the test? (Round your answer to one decimal place.)<BR>\n" );
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document.write( "(b) If 40 units are needed for the test, approximately how many units should be shipped? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #769378 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=769378\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the formula is A[t] = A[0] * e ^ (-.0249 * t)<BR>\n" );
document.write( "when t = 2, the formula becomes A[2] = A[0] * e ^ (-.0249 * 2)<BR>\n" );
document.write( "this results in A[2] = 38.05678758.<BR>\n" );
document.write( "if A[2] is required to be 40, then the formula becomes 40 = A[0] * e ^ (-.0249 * 2)<BR>\n" );
document.write( "solve for A[0] to get A[0] = 40 / e ^ (-.0249 * 2) = 42.04243453<BR>\n" );
document.write( "to have 40 units available in 2 days, 42.04243453 units would need to be shipped.<BR>\n" );
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