document.write( "Question 930996: what is the probability of missing no more than 1 question by guessing on a 8 total true or false question test? \n" ); document.write( "
Algebra.Com's Answer #565394 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
This is a binomial distribution question.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "n = 8
\n" ); document.write( "p = 1/2 = 0.5\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's define the function B(k) to be the probability where the student misses k problems where \"0%3C=k%3C=8\". So it's defined in terms of the binomial distribution formula\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "B(k) = (n C k)*p^k*(1-p)^(n-k)\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's plug in the constants n = 8 and p = 0.5 to get\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "B(k) = (8 C k)*0.5^k*(1-0.5)^(8-k)
\n" ); document.write( "B(k) = (8 C k)*0.5^k*0.5^(8-k)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Since it asks \"what is the probability of missing no more than 1 question\" we want to find P(X <= 1) which means we need to evaluate B(0) and B(1). Then we add up those two values\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"P%28X+%3C=+1%29+=+B%280%29+%2B+B%281%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "-------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "P(Missing 0) = B(0) = (8 C 0)*(0.5^0)*(0.5)^(8-0) = 0.00390625\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "P(Missing 1) = B(1) = (8 C 1)*(0.5^1)*(0.5)^(8-1) = 0.03125\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "-------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now add up the two individual probabilities (PDF's) to get the cumulative probability (CDF)\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "B(0) + B(1) = 0.00390625+0.03125 = 0.03515625\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "P(X <= 1) = 0.03515625\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "-------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the probability of missing no more than 1 question is 0.03515625\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "------------------------------------------------------------------------------------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "If you need more one-on-one help, email me at jim_thompson5910@hotmail.com. You can ask me a few more questions for free, but afterwards, I would charge you ($2 a problem to have steps shown or $1 a problem for answer only).\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Alternatively, please consider visiting my website: http://www.freewebs.com/jimthompson5910/home.html and making a donation. Any amount is greatly appreciated as it helps me a lot. This donation is to support free tutoring. Thank you.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Jim\r
\n" ); document.write( "\n" ); document.write( "------------------------------------------------------------------------------------------------------------------------
\n" ); document.write( "
\n" );