document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=922148>Question 922148</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The amount of snowfall falling in a certain mountain range is normally distributed with a mean of 74 inches, and a standard deviation of 12 inches. what is the probability that the mean annual snowfall during 36 randomly picked years will exceed 76.8 inches? (I know the answer I do not know how to get the answer) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #559416 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=559416\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">   mean of 74 inches, and a standard deviation of 12 inches, n = 36<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29 ALIGN=MIDDLE  ALT=\"z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "x= 76.8, z = 2.8//(12/sqrt(36)) = 1.4<BR>\n" );
document.write( "P(xbar> 76.5) = P(z >1.4) = normalcdf(1.4, 100) = .0808  0r 8.08%<BR>\n" );
document.write( "z-test was used as Population SD is known and sample size > 30<BR>\n" );
document.write( "...........<BR>\n" );
document.write( "A NEED to know is what sample size is thought to be sufficient<BR>\n" );
document.write( "for using z-test WHEN Population SD is known...check with Your sources.<BR>\n" );
document.write( "...........<BR>\n" );
document.write( "Population SD unknown...t-test is generally called for.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=blue+%28x+-+mean%29%2Fblue%28s%2Fsqrt%28n%29%29 ALIGN=MIDDLE  ALT=\"t+=blue+%28x+-+mean%29%2Fblue%28s%2Fsqrt%28n%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > and tcdf function used.<BR>\n" );
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