Mean (μ) = 1.75 pounds
Standard deviation (σ) = 0.95 pounds
Sample size (n) = 60
First, we define the z-score for the sample mean distribution:
If the mean of a sample of 60 people is 1.73 pounds, the corresponding z-score is:
Then, the probability that the mean weight loss after one week on the pill for a random sample of 60 individuals will be 1.73 pounds or less is equivalent to:
Finally, using the standard normal distribution: