Answer:
Almost 2.5% of the students spent more than $275 in a semester.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 235
Standard deviation = 20
According to the standard deviation rule, almost 2.5% of the students spent more than what amount of money on textbooks in a semester?
95% of the measures are within 2 standard deviation of the mean. The other 5% are more than 2 standard deviations of the mean. Since the normal distribution is symmetric, 2.5% of those are below two standard deviations of the mean and 2.5% are more than two standard deviations above the mean.
235 + 2*20 = $275
Almost 2.5% of the students spent more than $275 in a semester.
