The distribution of the amount of money spent by students fo

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. According to the standard deviation rule, almost 2.5% of the students spent more than ___________ on textbooks in a semester. A. $195 B. $215 C. $235 D. $275 E. $295

Solution

According to standard devaition rule 55% observations are between mean -/+ 2*SD. Therefore, due to symmetry of normal mean +2*sd above contains 2.5% of the observations.

=> 235+2*20

= 235+40

= 275

Answer D) 275