7.2-1. The length of life of brand X light bulbs is assumed to be N(ux, 784). The length of life of brand Y light bulbs is assumed to be N(uy, 627) and independent of X. If a random sample of nx = 56 brand X light bulbs yielded a mean of x = 937.4 hours and a random sample of size ny = 57 brand Y light bulbs yielded a mean of y=988.9 hours, find a 90% confidence interval for #x-My-

7.2-1. The length of life of brand X light bulbs is assumed to be N(ux, 784). The length of life of brand Y light bulbs is assumed to be N(uy, 627) and independent of X. If a random sample of nx = 56 brand X light bulbs yielded a mean of x = 937.4 hours and a random sample of size ny = 57 brand Y light bulbs yielded a mean of y=988.9 hours, find a 90% confidence interval for #x-My-

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...

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Suppose reaction times for recognition of common words like red or green are normally distributed with μμ=220 milliseconds and σσ=32. A psychologist presents a sample of n=16 participants with words that include the names of colors. However, the color names are printed in a different color of ink. That is, the word red might be printed in blue ink, or green might be printed in red. For these words, the sample had a mean reaction time of M=240. a. Do these data indicate that presenting color names in another color changes reaction time? Use a two tailed test with αα=.05. b. Compute Cohen's d to measure the size of the treatment effect.
11.1.6
15. The dean of a university estimates that the mean number of classroom hours per week for full-time faculty is 10.0. As a member of the student council, you want to test this claim. A random sample of the number of classroom hours for eightfull-time faculty for one week is shown in the table below. At α=0.05, can you reject the dean's claim? Complete parts (a) through (d) below. Assume the population is normally distributed. 11.2 7.5 12.2 7.2 4.1 9.5 13.7 8.5 Question content area bottom Part 1 (a) Write the claim mathematically and identify H0 and Ha. Which of the following correctly states H0 and Ha? A. H0: μ>10.0 Ha: μ≤10.0 B. H0: μ≠10.0 Ha: μ=10.0 C. H0: μ<10.0 Ha: μ≥10.0 D. H0: μ≤10.0 Ha: μ>10.0 E. H0: μ≥10.0 Ha: μ<10.0
A weight-loss program wants to test how well their program is working. The company selects a simple random sample of 51 individual that have been using their program for 15 months. For each individual person, the company records the individual's weight when they started the program 15 months ago as an x-value. The subject's current weight is recorded as a y-value. Therefore, a data point such as (205, 190) would be for a specific person and it would indicate that the individual started the program weighing 205 pounds and currently weighs 190 pounds. In other words, they lost 15 pounds. When the company performed a regression analysis, they found a correlation coefficient of r = 0.707. This clearly shows there is strong correlation, which got the company excited. However, when they showed their data to a statistics professor, the professor pointed out that correlation was not the right tool to show that their program was effective. Correlation will NOT show whether or not there is…
To compare the dry braking distances from 30 to 0 miles per hour for two makes of automobiles, a safety engineer conducts braking tests for 35 models of Make A and 35 models of Make B. The mean braking distance for Make A is 43 feet. Assume the population standard deviation is 4.6 feet. The mean braking distance for Make B is 46 feet. Assume the population standard deviation is 4.5 feet. At α=0.10, can the engineer support the claim that the mean braking distances are different for the two makes of automobiles? Assume the samples are random and independent, and the populations are normally distributed. The critical value(s) is/are Find the standardized test statistic z for μ1−μ2.
A sample of n= 25 scores has mean of m=68. Find the Z score for this this sample: A) If it was obtained from a population with mu= 60 and sigma=10 Z=___ B) if it was obtained from a population with mu= 60 and sigma =20 Z=__ C) if it was obtained from a population with mu= 60 and sigma = 40 Z= __
7. Suppose a teacher looks at a random sample of 42 final exam completion times and finds a mean timeof 111 minutes with asamplestandard deviation of 44 minutes. Which equation should they use tocompute the margin of error?A.E=s√nB.E=z√pqnC.E=zs√nD.E=ts√nE.E=t√pqn 8. Suppose a teacher looks at a random sample of 42 final exam completion times and finds a mean timeof 111 minutes with asamplestandard deviation of 44 minutes. Which value best approximates themargin of error for a 95% confidence interval?A.E= 6.8B.E= 33.4C.E= 13.3D.E= 13.7E.E= 34.4 9. A TWISTER spinner has four outcomes; red, blue, yellow, green. Tim believes that the proportion ofred outcomes is not equal to 25%. Which of the following correctly depicts hisnull hypothesis,H0?A.H0:μ >25B.H0:μ= 25C.H0:μ <25D.H0:μ6= 25E.H0:p=.25F.H0:p > .25G.H0:p < .25H.H0:p6=.25Page 2 10. A TWISTER spinner has four outcomes; red, blue, yellow, green. Tonya tests the claim that theproportion of red…
9.1 Q 8 ignore this, just to rememebr what question it is.
1. A single scalar ß is measured by m different people. Assuming un- correlated measurement errors of equal variance, show that the minimum-variance unbiased estimate of ß is equal to the average of the m measurement values.