document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=880387>Question 880387</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi - I know this is probably really simple, are I do not know if I am on the right track for this question (probability is just not making any sense to me at all).  \r<BR>\n" );
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document.write( "It is known that 25% of all staff in a company make use of the free influenza vaccination programme. Answer the following as:  The probability is equal to:  (Round your probability to 4 decimal places:\r<BR>\n" );
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document.write( "Q  If 20 people are randomly selected, find the probability that 8 or more people use the vaccine programme.\r<BR>\n" );
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document.write( "So if it is known that 25% of staff make use of the programme, then we can say 75% of staff do not.  After that I am stuck.  \r<BR>\n" );
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document.write( "Please help!<BR>\n" );
document.write( "Thanks in advance!\r<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #531419 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=531419\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is a sampling distribution of proportion, we know<BR>\n" );
document.write( "sample size is 20 and P(probability of taking vaccination) = .25 and Q(probability of not taking vaccination) = .75<BR>\n" );
document.write( "mean of p is .25 and standard deviation of p is square root (PQ/ n) where n is the sample size, therefore<BR>\n" );
document.write( "standard deviation of p is square root ((.25 * .75)/ 20) = 0.096824584<BR>\n" );
document.write( "now 8/20 = .4<BR>\n" );
document.write( "calculate the z value = (.4 - .25) / 0.096824584 = 1.549<BR>\n" );
document.write( "consult table of z values for probability associated with the z value<BR>\n" );
document.write( "therefore P(X<8) is 0.9393<BR>\n" );
document.write( "P(X>8) = 1 - P(X<8)<BR>\n" );
document.write( "and P(X>8) = 1 - 0.9393 = 0.0607\r<BR>\n" );
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