Solution :
Given that ,
mean = = 20
standard deviation = = 8
n = 75
= 20
= / n =8 / 75 = 0.9238
P( >18.5 ) = 1 - P( < 18.5)
= 1 - P[( - ) / < (18.5 -20) /0.9238 ]
= 1 - P(z <-1.62 )
Using z table
= 1 - 0.0526
= 0.9474
probability= 0.947
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