document.write( "Question 517777: An FBI survey showed that for about 80% of property crimes, criminals are never found and the case is never solved. Suppose that in a particular neighborhood there are repeated property crimes. The police are investigating six property crimes in this neighborhood.
\n" ); document.write( ". what is the probability that none of the crimes will be solved? .028
\n" ); document.write( "b. what is the probability that at least one will be solved? .972
\n" ); document.write( "c. what is the probability that 4 or more will not be solved?
\n" ); document.write( "d. what is the expected number of crimes that will be solved and what is the std. deviation?
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #344909 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
An FBI survey showed that for about 80% of property crimes, criminals are never found and the case is never solved. Suppose that in a particular neighborhood there are repeated property crimes. The police are investigating six property crimes in this neighborhood.
\n" ); document.write( "----------------------------------------------
\n" ); document.write( "Binomial Problem with n = 6 and p(not solved) = 0.8 p(solved) = 0.2
\n" ); document.write( "-------
\n" ); document.write( "a. what is the probability that none of the crimes will be solved?
\n" ); document.write( "P(x = 0) = 0.8^6 = 0.2621
\n" ); document.write( "------------------------------------
\n" ); document.write( "b. what is the probability that at least one will be solved?
\n" ); document.write( "(x>= 1) = 1 - P(x = 0) = 1 - 0.2621 = 0.7379\r
\n" ); document.write( "\n" ); document.write( "c. what is the probability that 4 or more will not be solved?
\n" ); document.write( "P(4<= x <=6) = 1 - P(0<= x <=3) = 1 - binomcdf(6,0.8,3) = 0.9011
\n" ); document.write( "--------------------
\n" ); document.write( "d. what is the expected number of crimes that will be solved and what is the std. deviation?
\n" ); document.write( "---
\n" ); document.write( "E(x) = u = np = 6*0.2 = 1.2
\n" ); document.write( "std = sqrt[npq] = sqrt(1.2*0.8] = 0.9798
\n" ); document.write( "============================================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( "============ \r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );