You are performing a left-tailed t-test with a sample size of 23 If α=.01α=.01, find the critical value, to two decimal places. HINT: Remember to pay attention to whether you want a z-critical value (proportion) or t-critical value (mean with population standard deviation unknown

In a particular statistics exam, the 35th percentile of final exam score is 42, and the 70th  percentile of final exam score is 76. A histogram of the scores approximately follows the normal curve. What is the approximate standard deviation of the final exam scores? Hints: What is the z value in the normal table that gives you closest to 35% of the area between -z and z? Now what does that tell you about the number of SDs in between 42 inches and 76 inches? You might find it helpful to draw a picture of the normal curve with original units and standard units. Group of answer choices a. 7.5 b. 13.1 c. 20.7 d. 37.8

The manufacturer claims that your new car gets 24 mpg on the highway. You suspect that the mpg is less for your car. The 44 trips on the highway that you took averaged 22.3 mpg and the standard deviation for these 44 trips was 4.2 mpg. What can be concluded at the  αα = 0.05 level of significance? For this study, we should use (t-test for population mean, z-test for population proportion)    The null and alternative hypotheses would be:       H0: (symbol) (symbol) ____                H1:  (symbol) (symbol) ____             The test statistic (?,t,z)    =  (please show your answer to 3 decimal places.) The p-value =  (Please show your answer to 4 decimal places.) The p-value is (?, less than or equal to, more than)  αα Based on this, we should (accept, reject, fail to reject) the null hypothesis. Thus, the final conclusion is that ... The data suggest that the sample mean is not significantly less than 24 at αα = 0.05, so there is statistically insignificant evidence to conclude…

You want to obtain a sample to estimate a population mean age. Based on previous evidence, you believe the population standard deviation is approximately o = 2.3 years. You would like to be 95% confident that your estimate is within 0.75 years of the true population mean. What is the smallest sample size you can use? The smallest possible sample has members.

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 4.6 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 14 samples is 4.9 ppm with a variance of 1.2 Does the data support the claim at the 0.01 level? Assume the population distribution is approximately normal. Step 2 of 5 :   Find the value of the test statistic. Round your answer to three decimal places.

"A fitness coach woud like to determine whether her aerobic fitness intervention leads to a significant increase or decrease in the one rep max (i.e., heaviest possible weight that can be lifted once) for deadlifts in her group of athletes (n = 13). She finds that the mean difference = 3 lbs, with a sum of squared deviation (SS) = 84. Calculate the t-statistic the fitness coach would observe given this data. (Be sure to round your answer to the second decimal place)."

Using a standardized scale, the average rating of behavioral problems for kindergarten children is ?μ= 35. A sample of n = 16 kindergarten children who had spent at least 20 hours per week in child care produced a mean score of M = 42.7 with a standard deviation of s = 6. Are the data sufficient to conclude that children in child care show significantly more behavioral problems than the average kindergarten children? use ?α = .01.

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the standard deviation is approximately s=24.3s=24.3. You would like to be 90% confident that your esimate is within 2 of the true population mean. How large of a sample size is required? Show your work.