A study was done to compare the amount of time per day students at public and private universities spend on Facebook. The study was composed of 200 students from a private university and 300 students from a public university. The time that students at a private university spent on Facebook had a normal distribution with of mean of 220 minutes and a standard deviation of 36 minutes.The time that students at a public university spent on Facebook had a normal distribution with a mean of 200 minutes and a standard deviation of 49 minutes. What is the probability that students at a private university spend more time on Facebook than students at a public university?

A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 10 days following no advertisements, the mean was 18.3 purchasing customers with a standard deviation of 1.8 customers. On 7 days following advertising, the mean was 19.4 purchasing customers with a standard deviation of 1.6 customers. Test the claim, at the 0.02 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 3 of 3: Draw a…

The amount of pretzels dispensed into a 24- ounce bag by the dispensing machine has been identifed as possessing a normal distribution with a mean of 24.5 ounces and a standard deviation of 0.2 ounce.  What pretzel amount represents the 67th  percentile for the bag weight distribution.

Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of women

The heights of 10 year old American children are normally distributed with a mean height of 4 feet and 5 inches (or 53 inches) and a standard deviation of 4.5 inches.In order to be allowed to go on a particular kids ride at the amusement park, children must be at least 44.9 inches tall and no more than 59.75 inches tall.What percent of 10 year old American children cannot go on the ride?

A sports writer wants to see if a football filled with helium travels farther, on average, than a football filled with air. 12 footballs were filled with helium to the recommend pressure and 15 footballs were filled with air to the recommended pressure. The mean yardage for the helium filled footballs was 267 yards with a standard deviation of 3 yards. The mean yardage for the air filled footballs was 241 yards with a standard deviation of 5 yards. Assume the populations are normal with equal variances. (a). Construct a 99% confidence interval for the mean difference in in yardage for the two types of footballs Lower bound (use 3 decimal places) Upper bound (use 3 decimal places) (b). What can you conclude about the sports writer's idea that helium footballs travel farther, on average? The helium footballs are no different than the other footballs, on average The other footballs travel farther on average than the helium footballs The helium footballs travel farther on average than the…

The mean attention span for a ten-year-old in the USA is 19.10 minutes with a standard deviation of 2.03 minutes. Dr. Nintendoaddict think that video game playing may increase attention span. Dr. Nintendoaddict surveys 25 ten-year-olds who regularly play video games and measure their attention span. Dr Nintendoaddict find that the video game players’ mean attention span is 20.85 minutes with a standard deviation of 2.45 minutes.   What is the critical value of z for alpha = .05?

The owners of the Metro Cash & Carry wished to study customers’ shopping habits. From earlier studies, the owners were under the impression that a typical shopper spends 0.7 hour at the mall, with a standard deviation of 0.10 hour. Recently the owners added some specialty restaurants designed to keep shoppers in the mall longer. A research team was hired to evaluate the effects of the restaurants. A sample of 45 shoppers by the team revealed that the mean time spent in the mall had increased to 0.80 hour. i. Develop a hypothesis test to determine if the mean time spent in the mall changed. Use the .10 significance level. ii. Suppose the mean shopping time actually increased from 0.75 hour to 0.79 hours. What is the probability of making a Type II error? iii)When research team reported the information in part (b) to the mall owners, the owners believed that the probability of making a Type II error was too high. How could this probability be reduced? plz sove it…

A blood bank is conducting a study on how much time is required of their patients for blood platelet donations. Based on past records, time spent in the waiting room has a mean of 5 minutes and a standard deviation of 1 minute, time spent with a nurse who reviews patients' medical records and measures their vital signs has a mean of 10 minutes and a standard deviation of 3 minutes, and the actual donation time has a mean of 130 minutes and a standard deviation of 8 minutes. Assuming these three times are independent and can all be modeled using a normal distribution, approximately what proportion of donors finish the entire donation process in under 2.5 hours (150 minutes)? (A) 0.66 (B) 0.72 (C) 0.84 (D) 0.89 (E) 0.99

A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 7 days following no advertisements, the mean was 22.1 purchasing customers with a standard deviation of 1.2 customers. On 10 days following advertising, the mean was 24.1 purchasing customers with a standard deviation of 1.6 customers. Test the claim, at the 0.05 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 1 of 3: State the…