1.Using the Z table to find the critical value(s) for each (P 407)
a) a = 0.04, left-tailed test
b) a = 0.05, two-tailed test
c) a = 0.005, right-tailed test
2.Write down the hypothesis for each of the following: (P 400, 401, 410)
a) An additive is claimed to improve automotive battery life (mean: 3 years)
b) Robot can reduce car assembly manufacturing defect to less than 20 C/100
c) Music is known to affect the test score (mean: 80) but do not know better or worse
e) Good job opportunity affect the college student age (ave: 25 yrs)
3. a) Walking (µ = 5 000 steps/day and s = 600 steps/day) is shown to improve health. A group of 40
health-conscious employees take average of 5430 steps/day. At a = 0.05 can it be concluded
that they walked more than the mean? (P 411)
b) US Senators (µ = 60 yrs and population s = 6.5 yrs), while state senators may be different.
A random sample of 40 from various states has an average of 55 years.
At a = 0.05 is there sufficient evidence that state senators are younger on average?
c) State whether the null hypothesis should be rejected on the basis of given P value (P 417)
I) P value = 0.258 a = 0.05, one-tailed test II) P value = 0.0684 a = 0.10, two-tailed test
d) Home prices in two cities were compared to see if there is a difference at a = 0.01. (P 474)
Scott X1 bar = $93,430, s1= $5602, n1 = 35;
Ligonier X2 bar = $98,043, s2 = $4731, n2 = 40
Is there enough evidence to reject the claim that the average price is the same?
4.PGA Golf Scores At a recent PGA tournament (the Honda Classic at Palm Beach Gardens, Florida) the following scores were posted for eight randomly selected golfers for two consecutive days.
(a) At a = 0.05, is there evidence of a difference in mean scores for the two days?
(b) Find the 95% confidence interval of the difference in the means.
Golfer1 2 3 4 5 6 7 8
Thursday67 65 68 68 68 70 69 70
Friday 68 70 69 71 72 69 70 70
5. Prices of Low-Calorie Foods The average price of a sample of 12 bottles of diet salad dressing taken from different stores is $1.43. The standard deviation is $0.09. The average price of a sample of 16 low-calorie frozen desserts is $1.03. The standard deviation is $0.10.
(a) At a = 0.01, is there a significant difference in price?
(b) Find the 99% confidence interval of the difference in the means.