The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes with a sample standard deviation of 0.5 minutes. We want to determine whether or, not the mean waiting time of all customers is significantly different than 3 minutes. Then the correct set of hypotheses is Select one: O a. HO: u 3 H1: u = 3.1 O b. HO: µ = 3 H1: µ # 3 O c. HO: µ + 3 H1: µ = 3 d. H0: μ- 3.1 H1: u # 3

If all the possible random samples with n- 36 scores are selected from a normal population with p- 80 and o - 18, and the mean is calculated for each sample, what is the average of all the sample means? O80 O 2 o Cannot be determined from the information given

If all the possible random samples with n = 36 scores are selected from a normal population with µ = 80 and σ = 18, and the mean is calculated for each sample, then what is the average of all the sample means? ​   a. ​80   b. ​6   c. ​2   d. ​It cannot be determined without additional information.

A sample mean for a treated group of n = 9 individuals is 32 and the population mean for the untreated group is 26. If the sample standard deviation is 9 ( is unknown), which of the following test statistics is correct? O z = .67 O z = 2.0 Ot=.67 O t = 2.0

The mean weight of a fire ant worker is 3.11 mg with a standard deviation of .49 mg. Suppose we randomly select 14 different fire ant workers having weights F1, F2, …, F14. Let S = F1 + F2 + ...+F14 and let M = S/14. This means S is the sample sum and M is the sample mean of the selected ant weights. (Note: random selection means F1 … F14 are independent.). Assume the Fi’s are normally distributed. j) What is the expected value of M - 3.11 ? k) What is the standard deviation of [(M - 3.11)/49]/srt14

1. A population has the numbers 2, 4, 6, 8, 10, 12. Then two samples are taken at random and without replacement. If it is known µ-7. Find: a. Population variance (0²) b. The mean standard deviation of the sample (ox²)

A researcher selects a sample of 9 observations from a population with a mean of 8 and a standard deviation of 3. About 16% of the sample means in this sampling distribution should be between a sample mean of O 7 and 8 There is not enough information to answer this. O9 and 10 07 and 9

Let x be a random variable representing the starting salary of a first-year teacher in a city. A report claims that the mean starting salary of these first-year teachers is greater than $50,000. To test this claim we find that a random sample of 20 teachers has a mean starting salary of $51,425 with a sample standard deviation of $3,549. If you assume that the population mean is $50,000, find the P-value corresponding to the hypothesis that the mean starting salary of the first-year teachers is greater than $50,000.

The results from a statistics class' first exam are as follows: The average grade obtained on the exam by its 45 students is an 85, with a standard deviation of 15 points. Answer the following based on this information: What z-score is required to be in the top 40%? QUESTION 45 The results from a statistics class' first exam are as follows: The average grade obtained on the exam by its 45 students is an 85, with a standard deviation of 15 points. Answer the following based on this information: What percentage of individuals have a z-score between -1 and 1.40? QUESTION 46 The results from a statistics class' first exam are as follows: The average grade obtained on the exam by its 45 students is an 85, with a standard deviation of 15 points. Answer the following based on this information: What percentage of individuals have a z-score between 1.05 and 1.40?

9.13 Given a sample size of 36, how large does the population standard deviation have to be in order for the standard error to be A. 1? B. 2? C. 5? D. 100?