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Q 17.

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The Practice of Statistics for AP Examination
Found in: Page 718
The Practice of Statistics for AP Examination

The Practice of Statistics for AP Examination

Book edition 6th
Author(s) Daren Starnes, Josh Tabor
Pages 837 pages
ISBN 9781319113339

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Short Answer

Skittles® Statistics teacher Jason Mole sky contacted Mars, Inc., to ask about the color distribution for Skittles candies. Here is an excerpt from the response he received: “The original flavor blend for the Skittles Bite Size Candies is lemon, green apple, orange, strawberry and grape. They were chosen as a result of consumer preference tests we conducted. The flavor blend is 20 percent of each flavor.”

a. State appropriate hypotheses for a significance test of the company’s claim.

b. Find the expected counts for a random sample of 60 candies.

c. How large a χ2 test statistic would you need to have significant evidence against the company’s claim at the α=0.05 level? At the α=0.01 level?

d. Create a set of observed counts for a random sample of 60 candies that gives a P-value between 0.01 and 0.05 Show the calculation of your chi-square test statistic.

Part (a) H0 : plemon = 0.20, plim e = 0.20, porange = 0.20, pstrawberry = 0.20, pgraph = 0.20

Ha : At least one of the pis is incorrect.

Part (b) Expected count for each flavor is 12

Part (c) If chi square statistic is greater than above critical values at specified level of significance then reject H0

Part (d)

See the step by step solution

Step by Step Solution

Part (a) Step 1: Given information

The flavor blend is 20% of each flavor.

Sample size is 60 candies.

Part (a) Step 2: Calculation

The null and alternative hypotheses:

H0 : plemon = 0.20, plim e = 0.20, porange = 0.20, pstrawberry = 0.20, pgrape = 0.20

H0 : At least one of the pis is incorrect.

Part (b) Step 1: Calculation

To get the predicted count, multiply each frequency of flavor by 60 As a result, the projected count is,

Part (c) Step 1: Calculation

The degrees of freedom = df = c-1

The df = 5-1 = 4

For each degree of significance, various critical values will be used.

When significance level = a = 0.05

χ2 = 9.49 Using excel formula, =CHIINV(0.05,4)χ2 = 13.28 Using excel formula, =CHIINV(0.01,4)

Reject H0 if the chi square statistic is greater than the crucial values at the selected level of significance.

Part (d) Step 1: Calculation

The frequency of the random sample is shown in the table below:

Using excel,

Therefore, the p-value is between 0.01 and 0.05

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