6.58. Pizza Refer to Problem 6.33 on pizza sizes. The 43 Dominos pizzas had mean

Question

6.58. Pizza Refer to Problem 6.33 on pizza sizes. The 43 Dominos pizzas had mean 28.81 cm and standard deviation 0.801 cm. The 39 Eagle Boys pizzas had mean 29.70 cm and standard deviation 0.550 cm. Note: The DF 74.7 (a) Make a 95% CI for the difference in the means. Cotnplete even if you don't think the conditions are met. Use the output in Problem 6.33 to check conditions. (b) Your friend looks at the sample means and says, "Big Deal. Eagle Boys has about 0.9 cm more pizza." That statement makes no sense. Why? (Hint: Think geometrically!) cin inore pizza

Explanation / Answer

(a)

The formula for estimation is:

1 - 2 = (M1 - M2) ± ts(M1 - M2)

where:

M1 & M2 = sample means
t = t statistic determined by confidence level
s(M1 - M2) = standard error = ((s2p/n1) + (s2p/n2))

Calculation

Pooled Variance
s2p = ((df1)(s21) + (df2)(s22)) / (df1 + df2) = 0.94 / 80 = 0.48

Standard Error
s(M1 - M2) = ((s2p/n1) + (s2p/n2)) = ((0.48/43) + (0.48/39)) = 0.15

Confidence Interval
1 - 2 = (M1 - M2) ± ts(M1 - M2) = 0.89 ± (1.99 * 0.15) = 0.89 ± 0.305

Result

1 - 2 = (M1 - M2) = 0.89, 95% CI [0.585, 1.195].

You can be 95% confident that the difference between your two population means (1 - 2) lies between 0.585 and 1.195.

(b) Mean is the average of all sizes, so one can't comment that entity A, has got 0.9 cm more than entity B.

Related Questions

Navigate

• Browse (All)
• Browse 6
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.