document.write( "Question 1174294: Let X be a random variable normally distributed with parameters μ= 70, σ= 10. Estimate P(65\n" ); document.write( "(Give the probability in the form of a decimal number (example: 0.123)!\r
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\n" ); document.write( "\n" ); document.write( "This is the question that I have and I have done it this way.
\n" ); document.write( "P8(65\n" ); document.write( "Z(85) = (85-70)/10 = 1.5
\n" ); document.write( "P(X<85) = 0.066807\r
\n" ); document.write( "\n" ); document.write( "Z(65) = (65-70)/10 = -0.5\r
\n" ); document.write( "\n" ); document.write( "However, I am not quite sure how I get P, I used an online calculator, and in the results it should be 0.624
\n" ); document.write( "> pnorm(85,70,10)-pnorm(65,70,10)=0.6246553\r
\n" ); document.write( "\n" ); document.write( "Can someone explain this to me? Thank you. \n" ); document.write( "
Algebra.Com's Answer #799720 by ewatrrr(24785)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Hi\r\n" );
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document.write( "μ= 70, σ= 10.\r\n" );
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document.write( "IF You mean between P( 65 ≥ x ≤ 85)\r\n" );
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document.write( "One can directly find that:  normcdf(65,85,70,10) =  .624\r\n" );
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document.write( "IF You are trying to estimate P (x=65),  normcdf(64.5,65.5,70,10) = .0352\r\n" );
document.write( "recommend smaller boundaries:\r\n" );
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document.write( " P (x ≤ 65.5) is .3264  \r\n" );
document.write( " P (x ≤ 64.5) is .2912\r\n" );
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document.write( " P(x= 65)  = (.3264 - .2912)   = .0352\r\n" );
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document.write( "Or \r\n" );
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document.write( "Wish You the Best in your Studies.\r\n" );
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