Managers at an automobile manufacturing plant would like to estimate the mean completion time of an assembly line operation, μ. The managers plan to choose a random sample of completion times and estimate μ via the sample. Assuming that the standard deviation of the population of completion times is 10.2 minutes, what is the minimum sample size needed for the managers to be 95% confident that their estimate is within 2.2 minutes of μ? Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satisfies the requirements).

Assume the data set described is normally distributed with the given mean and standard deviation, and with n total values. Find the approximate number of data values that will fall in the given range. Mean-8 Standard deviation-1.5 n-45 Range: 6.5 to 9.5 In this case, we expect about 52 data values to fall between 6.5 and 9.5.

A certain manufacturer makes 400w light bulbs. Assume that these light bulbs have lifetimes that are normally distributed with a mean lifetime of 480 hours and a standard deviation of 50 hours. Use this table or the ALEKS calculator to find the percentage of light bulbs with lifetimes shorter than 384 hours. For your intermediate computations, use four or more decimal places. Give your final answer to two decimal places (for example 98.23%). % X Español

An IQ test is designed so that the mean is 100 and the standard deviation is 10 for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of statistics students such that it can be said with 99% confidence that the sample mean is within 4 IQ points of the true mean. Assume that σ=10 and determine the required sample size using technology. Then determine if this is a reasonable sample size for a real world calculation.

Because the mean is very sensitive to extreme values, it is not a resistant measure of center. By deleting some low values and high values, the trimmed mean is more resistant. To find the 10% trimmed mean for a data set, first arrange the data in order, then delete the bottom 10% of the values and delete the top 10% of the values, then calculate the mean of the remaining values. Use axial loads (pounds) of aluminum cans listed below for cans that are 0.0111 in. thick. Identify any outliers, then compare the median, mean, 10% trimmed mean, and 20% trimmed mean. 247 261 269 273 275 280 282 282 284 285 285 287 290 292 293 296 296 299 311 507 Identify any outliers. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. The outlier(s) is/are pounds. (Type a whole number. Use a comma to separate answers as needed.) C OB. There are no outliers.

You collected data from a random sample of students on their impressions of the university.  On a particular opinion item item, the mean for male students was 15.2 -- with a standard deviation of 3.4. The mean on that item for women was 14.4, with a standard deviation of 3.8. Calculate Cohen's d effect size. IN THE SPACE BELOW, write the effect size AND your interpretation of it.

A reading class can read an mean of 175 words per minute and a population standard deviation of 20 words per minutes.  The top 3% of the class is to receive a special award for a random sample of 49 students. What is the minimum average number of words per minute a student would need to read in order to get the award for a random sample of 49 students?  Assume the data is normally distributed.