Question 1106626
Using the normal distribution, z-values need to be calculated for a, b, c
:
z-value = (X - mean) / standard deviation
:
a) z-value = (60 - 90) / 10 = -3.0
lookup the probability(P) associated with a z-value = -3.0
P ( X < 60 ) = 0.0013 = 0.13%
:
b) P ( X > 100 ) = 1 - P ( X < 100 ) 
z-value = ( 100 - 90 ) / 10 = 1.0
P ( X < 100 ) = 0.8413
P ( X > 100 ) = 1 - 0.8413 = 0.1587 = 15.87%
:
c) z-value = (110 - 90 ) / 10 = 2.0
P ( X < 110 ) = 0.9772
P ( X > 110 ) = 1 - 0.9772 = 0.0228
200 * 0.0228 = 4.56 approximately 5 students
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