The mean income of a group of summer students is $500 per week, the standard deviation is $55. If the income symmetrical and normally distributed. Use Empirical rule to answer the following questions: a) What percentage of students earned more than $445 a week? b) 2.5% of the students earned lower than what amount? c) What percent of students earned between $500 and $610? d) 16% of students earn lower than what amount