According to a survey, only 15% of customers who visited the web site of a major retail store made a purchase. Random samples of size 100 are selected. What is the probability that the sample proportion will have between 20% and 35% of customers who will make a purchase after visiting the web site?

According to a survey, only 18% of customers who visited the web site of a major retail store made a purchase. Random samples of size 80 are selected. What is the probability that the sample proportion will have between 15% and 20% of customers who will make a purchase after visiting the web site?

The Hawkins Company randomly samples 10 items from every large batch before the batch is packaged and shipped. According to the contract​ specifications, 5 percent of the items shipped can be defective. If the inspectors find 1 or fewer defects in the sample of​ 10, they ship the batch without further inspection. If they find 2 or​ more, the entire batch is inspected. Based on this sampling​ plan, the probability that a batch that contains twice the amount of defects allowed by the contract requirements will be shipped without further inspection is approximately 0.3874.

A survey showed that 76​% of adults need correction​ (eyeglasses, contacts,​ surgery, etc.) for their eyesight. If 14 adults are randomly​ selected, find the probability that at least 13 of them need correction for their eyesight. Is 13 a significantly high number of adults requiring eyesight​ correction?

According to Quantcast analytics of Crossfits.com, 40% of Crossfitters have post-graduate degrees. Suppose we take a random sample of 60 crossfitters. a. Describe the sampling distribution of the sample proportion of Crossfitters who have post-graduate degrees for samples of size 60. b. Find the probability that at least half of the sample 60 Crossfitters have post-graduate degrees.  c. Describe the sampling distribution of the sample proportion of Crossfitters who have post-graduate degrees for samples of size 100

Based on a smartphone​ survey, assume that 57​% of adults with smartphones use them in theaters. In a separate survey of 264 adults with​ smartphones, it is found that 149 use them in theaters. a. If the57% rate is​ correct, find the probability of getting 149 or fewer smartphone owners who use them in theaters. b. Is the result of 149 significantly​ low?

Based on a smartphone​ survey, assume that 57​% of adults with smartphones use them in theaters. In a separate survey of 224 adults with​ smartphones, it is found that 111 use them in theaters. a. If the 57​% rate is​ correct, find the probability of getting 111 or fewer smartphone owners who use them in theaters.

A survey of property owners' opinions about a street-widening project was taken to determine if owners' opinions were related to the distance between their home and the street. A randomly selected sample of 100 property owners was contacted and the results are shown next.     Opinion  Front Footage For Undecided Against  Under 45 feet 12 4 4  45-120 feet 35 5 30  Over 120 feet 3 2 5 What is the expected frequency for people against the project and who have over 120 feet of property foot-frontage?   Select one: a. 1.1 b. 3.9 c. 5.0 d. 5.5

A study conducted by the Center for Disease Control that asked 15,000 students about their sleep habits showed that about 73% of high school students did not get the required 8 hours of sleep per night.  Let p̂ be the proportion of high school students who do not get 8 hours of sleep daily. Find the probability of selecting a sample of 15000 students in which between 70% and 75% of the students did not get 8 hours of sleep every day.

A survey showed that 71​% of adults need correction​ (eyeglasses, contacts,​ surgery, etc.) for their eyesight. If 8 adults are randomly​ selected, find the probability that at least 7 of them need correction for their eyesight. Is 7 a significantly high number of adults requiring eyesight​ correction?