document.write( "Question 1156906: a) Suppose that a civil service examination is designed so that 70% of all persons with an IQ of 90 can pass it. Find the probability that among 14 persons with an IQ of 90 who take the test
\n" ); document.write( "i. At most 5 will pass.
\n" ); document.write( "ii. At least 11 will pass.
\n" ); document.write( "iii. From 8 through 12 will pass
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #779780 by VFBundy(438)\"\" \"About 
You can put this solution on YOUR website!
i. At most 5 will pass.
\n" ); document.write( "
\n" ); document.write( "n = 14
\n" ); document.write( "p = 0.70
\n" ); document.write( "q = 0.30
\n" ); document.write( "
\n" ); document.write( "MEAN = np = 14(0.70) = 9.8
\n" ); document.write( "
\n" ); document.write( "SD = \"sqrt%28npq%29\" = \"sqrt%2814%2A%280.70%29%2A%280.30%29%29\" = 1.7146
\n" ); document.write( "
\n" ); document.write( "P(X ≤ 5) ---> P(X < 5 + 0.5) ---> P(X < 5.5)
\n" ); document.write( "
\n" ); document.write( "Z = \"%285.5+-+9.8%29%2F1.7146\" = -2.51
\n" ); document.write( "
\n" ); document.write( "On a z-table, -2.51 is equal to 0.0060. That means the area to the left of the curve is 0.0060. So, the probability \"at most 5 will pass\" is 0.0060.
\n" ); document.write( "
\n" ); document.write( "==============================================================
\n" ); document.write( "
\n" ); document.write( "ii. At least 11 will pass.
\n" ); document.write( "
\n" ); document.write( "n = 14
\n" ); document.write( "p = 0.70
\n" ); document.write( "q = 0.30
\n" ); document.write( "
\n" ); document.write( "MEAN = np = 14(0.70) = 9.8
\n" ); document.write( "
\n" ); document.write( "SD = \"sqrt%28npq%29\" = \"sqrt%2814%2A%280.70%29%2A%280.30%29%29\" = 1.7146
\n" ); document.write( "
\n" ); document.write( "P(X ≥ 11) ---> P(X > 11 - 0.5) ---> P(X > 10.5)
\n" ); document.write( "
\n" ); document.write( "Z = \"%2810.5+-+9.8%29%2F1.7146\" = 0.41
\n" ); document.write( "
\n" ); document.write( "On a z-table, 0.41 is equal to 0.6591. That means the area to the right of the curve is 0.3409. So, the probability \"at least 11 will pass\" is 0.3409.
\n" ); document.write( "
\n" ); document.write( "==============================================================
\n" ); document.write( "
\n" ); document.write( "iii. From 8 through 12 will pass.
\n" ); document.write( "
\n" ); document.write( "n = 14
\n" ); document.write( "p = 0.70
\n" ); document.write( "q = 0.30
\n" ); document.write( "
\n" ); document.write( "MEAN = np = 14(0.70) = 9.8
\n" ); document.write( "
\n" ); document.write( "SD = \"sqrt%28npq%29\" = \"sqrt%2814%2A%280.70%29%2A%280.30%29%29\" = 1.7146
\n" ); document.write( "
\n" ); document.write( "P(8 ≤ X ≤ 12) ---> P(8 - 0.5 < X < 12 + 0.5) ---> P(7.5 < X < 12.5)
\n" ); document.write( "
\n" ); document.write( "Z1 = \"%287.5+-+9.8%29%2F1.7146\" = -1.34
\n" ); document.write( "
\n" ); document.write( "Z2 = \"%2812.5+-+9.8%29%2F1.7146\" = 1.57
\n" ); document.write( "
\n" ); document.write( "On a z-table:
\n" ); document.write( "
\n" ); document.write( "-1.34 is equal to 0.0901
\n" ); document.write( "1.57 is equal to 0.9418
\n" ); document.write( "
\n" ); document.write( "Simply subtract 0.0901 from 0.9418 to get a result of 0.8517. So, the probability \"from 8 through 12 will pass\" is 0.8517.
\n" ); document.write( "
\n" );