document.write( "Question 1052174: Shipping line W deals with transportation of goods in containers of various sizes. Charges for each container depend on its weight. A consignment of 800 containers in a particular vessel is in the high seas. Records indicate that the weights are normally distributed. The chances of a container weighing more than 20 tonnes are 97,72% while the chances of a container weighing less than 42,55 tonnes are 99,4%.\r
\n" ); document.write( "\n" ); document.write( "(1) Determine the mean µ and the standard deviation of the weights of the containers.\r
\n" ); document.write( "\n" ); document.write( "(2) Charges of one tonne are £2,50. Determine the number of containers whose weights are more than the mean µ but not exceeding 32,2 tonnes. Hence or otherwise, determine the total charges on these containers.
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Algebra.Com's Answer #667601 by stanbon(75887)\"\" \"About 
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: Shipping line W deals with transportation of goods in containers of various sizes. Charges for each container depend on its weight.
\n" ); document.write( "A consignment of 800 containers in a particular vessel is in the high seas. Records indicate that the weights are normally distributed.
\n" ); document.write( "The chances of a container weighing more than 20 tonnes are 97.72% while the chances of a container weighing less than 42.55 tonnes are 99.4%.
\n" ); document.write( "(1) Determine the mean µ and the standard deviation of the weights of the containers.
\n" ); document.write( "z-value with a left tail of 1-0.9772 = 0.0228:: z = invNorm(0.0228)= -2
\n" ); document.write( "z-value with a left tail of 0.994 :: z = invNorm(0.994) = 2.5
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\n" ); document.write( "Use x = z*s + u
\n" ); document.write( "20 = -2*s + u
\n" ); document.write( "42.55 = 2.5s + u
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\n" ); document.write( "Subtract and solve for \"s\"::
\n" ); document.write( "22.55 = 4.5s
\n" ); document.write( "s = 5
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\n" ); document.write( "Solve for \"u\"::
\n" ); document.write( "20 = -2*5 + u
\n" ); document.write( "u = 30
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\n" ); document.write( "(2) Charges of one tonne are £2,50. Determine the number of containers whose weights are more than the mean µ but not exceeding 32.2 tonnes. Hence or otherwise, determine the total charges on these containers.
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\n" ); document.write( "z(32.2) = (32.2-30)/5 = 2.2/5 = 0.44
\n" ); document.write( "P(30< x < 32.2) = P(0< z <0.44) = normalcdf(0,0.44) = 17%
\n" ); document.write( "---
\n" ); document.write( "Charge = 0.17*800*2.5 = L340.06
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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