It is reported that American adolescents spend an average of μ =4 hours per day using smart phone (σ = 2 hours). Assuming the distribution is normal, a. What is the probability of selecting an individual who uses a smart phone more than 8 hours a day? b. what proportion of American adolescents spend between 2.5 and 5.5 hours per day using smart phones?

It is reported that American adolescents spend an average of μ =4 hours per day using smart phone (σ = 2 hours). Assuming the distribution is normal, a. What is the probability of selecting an individual who uses a smart phone more than 8 hours a day? b. what proportion of American adolescents spend between 2.5 and 5.5 hours per day using smart phones?

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

See similar textbooks

Similar questions

The time needed to complete a final examination in a particular college course is normally distributed with a mean of 160 minutes and a standard deviation of 25 minutes. Answer the following questions What is the probability of completing the exam in 120 minutes or less? What is the probability that a student will complete the exam in more than 120 minutes but less than 150 minutes? What is the probability that a student will complete the exam in more than 100 minutes but less than 170 minutes? Assume that the class has 120 students and that the examination period is 180 minutes in length. How many students do you expect will not complete the examination in the allotted time?
The state of California has a mean annual rainfall of 19 inches, whereas the state of New York has a mean annual rainfall of 48 inches (Current Results website, October 27, 2012). Assume that the standard deviation for both states is 4 inches. A sample of 30 years of rainfall for California and a sample of 45 years of rainfall for New York has been taken. a. Show the probability distribution of the sample mean annual rainfall for California. This is a normal probability distribution with and (to decimals). b. What is the probability that the sample mean is within inch of the population mean for California? (to decimals) c. What is the probability that the sample mean is within inch of the population mean for New York? (to decimals) d. In which case, part (b) or part (c), is the probability of obtaining a sample mean within inch of the population mean greater? Why? The probability of being within inch is greater because the sample size is .
The number of sales that a car salesperson makes per month is normally distributed with mean 15 and standard deviation 4 . a. Find the probability that a randomly selected car salesperson will sell more than 14 cars this month.b. What is the average number of cars that a group of 25 sales people must sell to be in the 90thpercentile?
Suppose a brewery has a filling machine that fills 12 ounce bottles of beer. It is known that the amount of beer poured by this filling machine follows a normal distribution with a mean of 12.23 ounces and a standard deviation of 0.04 ounce. Find the probability that the bottle contains fewer than 12.13
A report in 2010 indicates that Americans between the ages of 8 and 18 spend an average of μ = 7.5 hours per day using some sort of electronic device such as smart phones, computers, or tablets. Assume that the distribution of times is normal with a standard deviation of σ = 2.5 hours and find the following values. a. What is the probability of selecting an individual who uses electronic devices more than 12 hours a day? b. What proportion of 8- to 18-year-old Americans spend between 5 and 10 hours per day using electronic devices? In symbols, p(5 < X < 10) = ?
The table summarizes results from pedestrian deaths that were caused by automobile accidents. Pedestrian Deaths Driver Pedestrian Intoxicated? Intoxicated? Yes NO. 09 283 Yes 564 NO. If two different pedestrian deaths are randomly selected, find the probability that they both involved pedestrians that were not intoxicated. Report the answer rounded to four decimal place accuracy. Question Help: Written Example Message instructor Submit Question Jump to Answer 43,324 MAR 080 8.
A particular bakery makes a very popular peanut butter pie. Suppose daily demand follows a Normal distribution with mean 43 pies and standard deviation 5 pies. a. What is the probability that the demand is between 35 and 40 peanut butter pies in a day? b. What is the probability that the demand is greater than 50 pies a day? c. What is the demand that has a 1% chance of being exceeded?
A study indicates that 18 to 24-year olds spend a mean of 135 minutes watching video on their smartphones per month. Assume that the amount of time watching video on a smartphone per month is normally distributed and that the standard deviation is 10 minutes. What is the probability that an 18- to 24-year-old spends less than 130 minutes watching video on his or her smartphone per month? (please show me how you got the answer)
c. Vehicle speeds at a highway location have a normal distribution with mean u = 65 mph and standard deviation o = 5 mph. Find the probability that a randomly selected vehicle speed is greater than 73 mph.
The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.65.6 days and a standard deviation of 2.12.1 days. What is the probability of spending more than two days in recovery? A.) 0.9568 B.) 0.0432 C.) 0.8922 D.) 0.0401
A production line in a factory, assembles laptops. A random sample of assembly time of 36 laptops has been drawn from this factory. Suppose, the population distribution has a mean assembly time of 25 minutes and standard deviation 6 minutes. What is the probability that a sample mean is 26 minutes? Select one: a. 0.0 b. =P(Z>1) c. =P(Z=0) d. =P(Z<1) e. None of the others
Assume that cans of Coke are filled so that the actual amounts have a mean of 12.00 oz and a standard deviation of 0.11 oz. However, 36 random cans of coke were selected and found to have a mean of 12.19 oz. Find the probability that a single can of Coke has at least 12.19 oz.