1 The number of flaws in a glass sheet has a mean value of 0

1. The number of flaws in a glass sheet has a mean value of 0.8and a standard deviation of 0.7071. What is the probability that the total number of flaws in 100 sheets of glass is more than 85?

Solution

x= no. of flaws in a glass sheet!
Total no. of flaws in 100 sheets has the distribution....= N ( mean=100* 0.8 ,variance= 100 * ( 0.7071 ) ^2 )

so, mean = 80, s.d = 7.071.......
p( total no. of flaws >= 85 ) = p ( (total no. of flaws - mean) / s.d >= ( ( 85 - 80) / 7.071 ) )
=p ( z >= 0.707) = 1 - p ( z < 0.707 ) = 0.2397832......