Question 1026013
mean = 7.2
standard deviation = .15
threshold score = 7.425


calculate the z-score.


z-score = (threshold score minus mean) / standard deviation.


this becomes z-score = (7.425 - 7.2) / .15.


this results in z-score = .225 / .15 = 1.5.


look up a z-score of 1.5 in the z-score table and it will tell you that the area under the normal distribution curve to the left of a z-score of 1.5 is equal to .9332.


this means that the probability of having a ph score less than 7.425 is .9332.


the probability of having a ph greater than 7.425 is therefore 1 - .9332 = .0668.


that's a 6.68% probability.