Solution :
Given that,
variance = 2 = 7.29
Population standard deviation = = 2 = 7.29 = 2.7
Margin of error = E = 0.28
At 90% confidence level the z is,
= 1 - 90%
= 1 - 0.90 = 0.10
/2 = 0.05
Z/2 = 1.645
sample size = n = [Z/2* / E] 2
n = [1.645 * 2.7 / 0.28]2
n = 251.61
Sample size = n = 252
i need help with this questiong ASAP An educational psychologist wishes to know the mean number of words a third gra...
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to ensure that the estimate has an error of at most 0.25 words per minute. a previous study found that the mean was 25.8 words per minute. assuming that the variance is 9.61. what is the minimum number of third graders that must be included in a sample to construct the 98% confidence interval
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to ensure that the estimate has an error of at most 0.22 words per minute. A previous study found that the mean was 294 words per minute. Assuming that the standard deviation is 3.9. what is the minimum number of third graders that must be included in a sample to construct the 80% confidence interval Round your answer up to...
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to ensure that the estimate has an error of at most 0.2 words per minute. A previous study found that the mean was 26.3 words per minute. Assuming that the standard deviation is 4.3, what is the minimum number of third graders that must be included in a sample to construct the 85% confidence interval? Round your answer up to...
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to ensure that the estimate has an error of at most 0.32 words per minute. A previous study found that the mean was 25.7 words per minute. Assuming that the standard deviation is 5.6, what is the minimum number of third graders that must be included in a sample to construct the 85% confidence interval? Round your answer up to...
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to ensure that the estimate has an error of at most 0.26 words per minute. A previous study found that the mean was 36.7 words per minute. Assuming that the standard deviation is 4.5, what is the minimum number of third graders that must be included in a sample to construct the 85% confidence interval?
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at the 99 % level of confidence. For a sample of 1584 third graders, the mean words per minute read was 35.7 . Assume a population standard deviation of 3.3 . Construct the confidence interval for the mean number of words a third grader can read per minute. Round your answers to one decimal place.
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at the 98% level of confidence. For a sample of 1116 third graders, the mean words per minute read was 28.1. Assume a population standard deviation of 4.2. Construct the confidence interval for the mean number of words a third grader can read per minute. Round your answers to one decimal place.
help please and thank you NASA is conducting an experiment to find out the fraction of people who black out at G forces greater than 6. In an earlier study, the population proportion was estimated to be 0.36. How large a sample would be required in order to estimate the fraction of people who black out at 6 or more Gs at the 85% confidence level with an error of at most 0.04? Round your answer up to the next...
A fast food restaurant executive wishes to know how many fast food meals adults eat each week. They want to construct a 90%90% confidence interval with an error of no more than 0.070.07. A consultant has informed them that a previous study found the mean to be 7.47.4 fast food meals per week and found the variance to be 0.810.81. What is the minimum sample size required to create the specified confidence interval? Round your answer up to the next...
A research company desires to know the mean consumption of milk per week among males over age 25. They believe that the milk consumption has a mean of 2.3 liters, and want to construct a 90% confidence interval with a maximum error of 0.08 liters. Assuming a variance of 1.69 liters, what is the minimum number of males over age 25 they must include in their sample? Round your answer up to the next integer.