QUESTIONS
Question 1
James was eating a bag of candies that came in eight different colors. He noticed that there appeared to be far less green candies than any of the others and wondered if the true proportion of green candies is lower than the 12.5% that would be expected if all of the candies came in even amounts. For the sake of statistics, he decided that he would need to buy more candy to test his hypothesis. James randomly selected several bags of candies and recorded the color of each piece of candy. He found that out of the first 400 candies that he counted, 37 of them were green.
James conducts a one-proportion hypothesis test at the 5% significance level, to test whether the true proportion of green candies was lower than 12.5%.
(a) H0: p=0.125; Ha: p<0.125, which is a left-tailed test.
(b) Use Excel to test whether the true proportion of green candies is less than 12.5%. Identify the test statistic, z, and p-value from the Excel output, rounding to three decimal places.
Question 2
James was eating a bag of candies that came in eight different colors. He noticed that there appeared to be far less green candies than any of the others and wondered if the true proportion of green candies is lower than the 12.5% that would be expected if all of the candies came in even amounts. For the sake of statistics, he decided that he would need to buy more candy to test his hypothesis. James randomly selected several bags of candies and recorded the color of each piece of candy. He found that out of the first 400 candies that he counted, 37 of them were green.
James conducts a one-proportion hypothesis test at the 5% significance level, to test whether the true proportion of green candies was lower than 12.5%.
Which answer choice shows the correct null and alternative hypotheses for this test?
- H0: p=0.09; Ha: p<0.09, which is a left-tailed test.
- H0: p=0.125; Ha: p<0.125, which is a left-tailed test.
- H0: p=0.9; Ha: p>0.9, which is a right-tailed test.
- H0: p=0.125; Ha: p>0.125, which is a right-tailed test.
SOLUTIONS:
Question 1
James was eating a bag of candies that came in eight different colors. He noticed that there appeared to be far less green candies than any of the others and wondered if the true proportion of green candies is lower than the 12.5% that would be expected if all of the candies came in even amounts. For the sake of statistics, he decided that he would need to buy more candy to test his hypothesis. James randomly selected several bags of candies and recorded the color of each piece of candy. He found that out of the first 400 candies that he counted, 37 of them were green.
James conducts a one-proportion hypothesis test at the 5% significance level, to test whether the true proportion of green candies was lower than 12.5%.
(a) H0: p=0.125; Ha: p<0.125, which is a left-tailed test.
(b) Use Excel to test whether the true proportion of green candies is less than 12.5%. Identify the test statistic, z, and p-value from the Excel output, rounding to three decimal places.
Answer
Test statistic -1.965
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