Answer
Answer: z = 2.455
Work Step by Step
The area 0.993 is not on the standard normal distribution table. However, it falls between the probabilities 0.9929 and 0.9931 which are both on the standard normal distribution table. 0.9929 corresponds to a z score of 2.45 and 0.9931 corresponds to a z score of 2.46. The z score for 0.993 is halfway between those values.
So to find the z score corresponding to 0.993:
(2.45 + 2.46)/2 = 2.455
Therefore 0.993 corresponds to a z score of 2.455
