The manager of a computer retail store is concerned thathis suppliers have been giving him laptop computers withlower than average quality. His research shows thatreplacement times for the model laptop of concern arenormally distributed with a mean of 4.4 years and astandard deviation of 0.6 years. He then randomly selectsrecords on 53 laptops sold in the past and finds that themean replacement time is 4.2 years.a. Find the probability that 53 randomly selectedlaptops will have a mean replacement time of 4.2years or less. Round your answer to four decimalplaces.P(M 4.2 years)=b. Based on the result above, does it appear that thecomputer store has been given laptops of lower thanaverage quality?Yes. The probability from the sample showsthat there's a possibility that the owner is givenlaptops lower than average quality.No. The probability from the sample shows it isunlikely that the owner is given laptops lowerthan average quality.

From the given information :Mean , 4.4Standard deviation , 0.6

Answered: The manager of a computer retail store…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Some battery manufacturers claim that the average battery life of the company is 240 hours. There is a theory in the quality department of the company that the lifespan is different from 240 hours. The Quality Department therefore decided to conduct an experiment to test this theory. A random sample of size 18 was taken and the lifespan was examined. The average life of the batteries examined was 237,056 hours and the standard deviation was 11,280. Battery life can be expected to follow a normal distribution.a) Find a 95% confidence interval for the average battery life.b) Examine with an appropriate hypothesis test whether the average battery life differs from 240 hours.sometimes. Use α = 0.05.
According to the U.S. Census Bureau, the mean household income in the United States in 2000 was $57,045 and the median household income was $42,148.The variability of household income is quite large with an overall standard deviation of approximately $25000. Suppose a random sample of 225 households was selected. What is the probability that the sample mean would be above $60,245?
The producer of a weight-loss pill advertises that people who use the pill lose, after one week, an average (mean) of 1.8 pounds with a standard deviation of 1.05 pounds. In a recent study, a group of 45 people who used this pill were interviewed. The study revealed that these people lost a mean of 1.73 pounds after one week. If the producer's claim is correct, what is the probability that the mean weight loss after one week on this pill for a random sample of 45 individuals will be 1.73 pounds or more? Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.
The producer of a weight-loss pill advertises that people who use the pill lose, after one week, an average (mean) of 1.75 pounds with a standard deviation of 1.02 pounds. In a recent study, a group of 60 people who used this pill were interviewed. The study revealed that these people lost a mean of 1.9 pounds after one week. If the producer's claim is correct, what is the probability that the mean weight loss after one week on this pill for a random sample of 60 individuals will be 1.9 pounds or less? Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.
Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
For a standardized psychology examination intended for psychology majors, the historical data show that scores have a mean of 515 and a standard deviation of 170. The grading process of this year's exam has just begun. The mean score of the 35 exams graded so far is 518. What is the probability that a sample of 35 exams will have a mean score of 518 or more if the exam scores follow the same distribution as in the past? Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.
The producer of a weight-loss pill advertises that people who use the pill lose, after one week, an average (mean) of 1.8 pounds with a standard deviation of 0.95 pounds. In a recent study, a group of 45 people who used this pill were interviewed. The study revealed that these people lost a mean of 1.92 pounds after one week. If the producer's claim is correct, what is the probability that the mean weight loss after one week on this pill for a random sample of 45 individuals will be 1.92 pounds or less? Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.
This question applies to the next 3 MCQs. Wire wound resistors are being custom made for a Design House with a maximum specification of 305.70 ohms and a minimum specification of 304.55 ohms. If the resistance is higher it can be reworked, if lower they must be scrapped. The resistors manufactured follow a normal distribution with a mean of 305.2 ohms and a standard deviation of 0.25 ohms. What percentage of the resistors are scrap (approximately)? 5% 2% 0.1% 0.5% 1%
An engineer is going to redesign an ejection seat for an airplane. The seat was designed for pilots weighing between 130 lb and 181 lb. The new population of pilots has normally distributed weights with a mean of 136 lband a standard deviation of 29.6 lb. b. If 38 different pilots are randomly selected, find the probability that their mean weight is between 130 lb and 181 lb.

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