Answer: The z-score, also known as the standard score, is a measure of how many standard deviations an individual's score is from the mean. To calculate the z-score, we can use the following formula:
z-score = (x - μ) / σ
Where x is the individual's score, μ is the mean, and σ is the standard deviation.
In this case, the mean is 140, the standard deviation is 40, and the individual's score is 48. So, we can plug these values into the formula:
z-score = (48 - 140) / 40
z-score = -3
So, the person who scored 48 on the exam has a z-score of -3 which means the score is 3 standard deviation below the mean.
Explanation: