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Confidence intervals

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Wize University Statistics Textbook > Estimating with Confidence Intervals

Confidence Interval for a Proportion

3 Activities

Based on a sample of 800 children in Twin Pines, 82% of them are vaccinated. Interpret a 95% confidence interval [0.788, 0.852]\left[0.788,\ 0.852\right] in plain English.
More Confidence Interval for a Proportion Questions:
Confidence Interval
You are given an 99% confidence interval for the proportion of homeowners that still have a home phone →\rightarrow (0.35, 0.49)
1. What is an estimate for the proportion of homeowners having a home phone?
2. What is the standard error of the sample proportion of homeowners owing a home phone?
Confidence Interval for a Proportion
A random sample of 1000 people in Calgary were asked if they are satisfied with their mobile carriers: “YES or NO?” Results: 535 people said YES.
Confidence Interval for a Proportion
A random sample of 1000 people in Calgary were asked if they are satisfied with their mobile carriers: “YES or NO?” Results: 535 people said YES.
Confidence Interval for a Proportion
Based on a random sample of 200 households, 70 of them have at least one pet. Construct a 95% confidence interval for the households that has pets.
Confidence Interval for a Proportion
Parts (i) to (iv) are based on the following information:
In 2006, it was reported that only 40% of students at the university ask questions in lectures. It is believed that this percentage has changed. You randomly sampled 80 students and asked them "Have you ever asked a question in a lecture?" Twenty-four of them responded "Yes". There are 20,386 students at the university.
(iii) What is the p-value?
Population sampling
There are 600 Sephora locations in the United States. Christine randomly selected 40 stores, and then she randomly selected 100 customers from each of those stores. Less than 1% of her sample identified as heterosexual males. Based on her sample, the average spending at Sephora is $45. In addition, 340 customers in her sample revealed that they have VIB Rouge status, which the highest tier status that is reached when a customer spends $1,000 in a calendar year.
Which of the following is/are true? (Check all that applies.)
Confidence Interval for a Proportion
Based on a sample, the average time it takes a customer to eat a burger is 20 minutes with a standard deviation of 8 minutes. Furthermore, 27 customers in the sample ordered the vegetarian burger.
We are 95% confident that between 23.1% and 43.6% of all customers order the vegetarian burger. Construct a 95% confidence interval for the average time it takes all customers to eat a burger.
Confidence Interval for a Proportion
Which of the following is true for a 90% confidence interval for the population proportion.
Confidence Interval
You are given an 99% confidence interval for the proportion of homeowners that still have a home phone →\rightarrow (0.35, 0.49)
1. What is an estimate for the proportion of homeowners having a home phone?
2. What is the standard error of the sample proportion of homeowners owing a home phone?