A restaurant adds an automatic tip of $2, plus 15% of the bill. For example, if your bill is $20, you are charged a tip = $5. Last Saturday, the average bill at this restaurant was $45. What was the average tip charge?

a) $8.75

b) $9.00

c) $

9.25

d) $9.75

e) $10.40

suppose the standard deviation of bill amounts was $18. What was the standard deviation of tip sizes?

a) 1.18

b) 1.36

c) 1.54

d) 1.88

e) 2.70