8)       The braking distances of 9 Chevrolet Cobalts and 11 Toyota Camrys were

           tested in similar conditions. The results are given in this chart:

Cobalt Camry

= 142 feet = 147 feet

s₁ = 5.8 feet s₂ = 2.7 feet

n₁ = 9 n₂ = 11

At α = 0.05, can you conclude that there is a difference in the average braking distances of the two types of cars? Perform a hypothesis test for your decision.

9)       The prices for 15 randomly selected automobile batteries are shown in the

           table. The prices are classified according to battery type. Using an ANOVA

           test with α= 0.10, is there enough evidence to conclude that at least one

           of the mean battery prices is different from the others?

Group size 35 Group size 65 Group size 34/78

55 70 75

55 80 95

80 80 80

60 80 75

55 95

85

10)     A baseball team has the following win totals over 25 recent full seasons.

74, 67, 71, 76, 88, 92, 96, 98, 87, 95, 103, 101, 101, 95, 97, 94, 89, 103, 95, 97, 95, 85, 84, 87, 84

a)   Create a stem-and-leaf plot for the data.

if it is hard you can skip.

b)   Find and interpret a 90% confidence interval for the average number of wins for this particular team

c)    Many teams consider it a successful season if they finish the season with 85 wins. At α = 0.01, is there evidence to conclude that this team averaged a higher number of wins than that? Perform a hypothesis test to support your decision.

11) A local commerce expert believes that the day of the week that people order food for delivery is uniformly distributed. To test this, you randomly select 581 restaurants and record the day on which each order takes place. The results are shown below. Using a chi-square goodness-of-fit test at α = 0.05, test the claim.

Day Sunday Monday Tuesday Wednesday Thursday Friday Saturday

Orders 67 40 48 64 82 148 132

pur-new-sol

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