Suppose that the distribution of the lifetime of a car battery produced by a certain car company is well approximated by a normal distribution with a mean of 1300 hours and variance 104. What is the approximate probability that a batch of 100 car batteries will contain at least 20 whose lifetimes are less than 1205 hours?
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- Suppose a batch of metal shafts produced in a manufacturing company have a variance of 7.847.84 and a mean diameter of 201201 inches. If 8989 shafts are sampled at random from the batch, what is the probability that the mean diameter of the sample shafts would differ from the population mean by more than 0.20.2 inches? Round your answer to four decimal places.A psychologist obtains a random sample of 20 mothers in the first trimester of their pregnancy. The mothers are asked to play Mozart in the house at least 30 minutes each day until they give birth. After 5 years, the child is administered an IQ test. It is known that IQs are normally distributed with a mean of 100. If the IQs of the 20 children in the study result in a sample mean of 104.2 and sample standard deviation of 14, is there evidence that the children have higher IQs? Use the a = 0.05 level of significance. Complete parts (a) through (d). (a) Determine the null and alternative hypotheses. Ho: 100 H1: H > 100 (b) Calculate the P-value. P-value = (Round to three decimal places as needed.)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.
- 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 175. The grading process of this year's exam has just begun. The average score of the 40 exams graded so far is 518. What is the probability that a sample of 40 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. Sub ContinueIn a company, the known mean time before the first occupational accident is normally distributed with a mean of 12 years and a variance of 6.76 years². What is the probability that an individual happens to have an accident between 11.3 and 13.6 years of permanence in the company?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 175. The grading process of this year's exam has just begun. The average score of the 35 exams graded so far is 526. What is the probability that a sample of 35 exams will have a mean score of 526 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. Submit Assignment 2021 McGraw Hil LLC. All Rights Reserved. Terms of Use Privacy Center Accessibility US Continue V O 8:19 hp esc 2# 8. 3 4. t 00
- Suppose that the fraction of defective modems shipped by a data-communications vendor has an approximation beta distribution with a=5 and b=21. find the mean and variance of the fraction of defective modems per shipment What is the probability that a randomly selected shipment will contain at least 30 % defectives? What is the probability that a randomly selected shipment will contain no more than 5 % defectives?A manager tracks parts made by a machine. She collects data for 30 days. On 7 days 18 parts were made, on 9 days 6 parts were made, and on the remaining days 3 parts were broken. 1. What is the mean number of parts made? (round to 2-decimal) 2. What is the variance of the parts made? (round to 2-decimal) 3. What is the standard deviation of the parts made? (round to 2-decimal) 4. How many parts will be made in 250days?? (in whole parts)Suppose a college admissions test is normally distributed with a mean of 500 and a standard deviation of 100. If a student scores in the 75th percentile, what is their test score? If the top 10% of test takers are eligible for a scholarship, what is the minimum score needed to qualify for the scholarship? If the test is taken twice by the same student, and the scores are independent, what is the probability that their average score is above 550?
- A psychologist obtains a random sample of 20 mothers in the first trimester of their pregnancy. The mothers are asked to play Mozart in the house at least 30 minutes each day until they give birth. After 5 years, the child is administered an IQ test. It is known that IQs are normally distributed with a mean of 100. If the IQs of the 20 children in the study result in a sample mean of 104.3 and sample standard deviation of 16, is there evidence that the children have higher IQs? Use the a = 0.05 level of significance. Complete parts (a) through (d). (a) Determine the null and alternative hypotheses. Но V100 H : V 100 (b) Calculate the P-value. P-value = (Round to three decimal places as needed.) (c) State the conclusion for the test. Choose the correct answer below. O A. Do not reject Ho because the P-value less than the a = 0.05 level of significance. O B. Reject H, because the P-value is greater than the a= 0.05 level of significance. O C. Reject H, because the P-value is less than…Suppose a researcher pbserves a population of 12 people and computes SS=204. What is the variance? What is the standard deviation?