On average, a sample of n = 36 scores from a normal population with σ = 10 will provide a better estimate of the population mean than a researcher would get with a sample of n = 9 scores from a normal population with σ = 10.

A sample of n=25 scores has a mean of M=68. Find the z-score for this sample: if it was obtained from a population with u=60 and 0=10

In the general population, the mean IQ score is 100, with standarddeviation σ = 15. A random sample of 36 newly tested incoming students atCommunity College revealed a sample mean IQ of 104.5. Does this sample givegood evidence (at a 5% level of significance) that the mean IQ of allincoming students is different from 100?

suppose that 43% of people who enter a store will make a purchase. Random samples of people who walk into a particular store is studied, and the proportion of those who made a purchase is found for each sample. Assume that all the samples were the same size. If 29.46% of all sample proportions are less than 0.3274. What was the z-score for 0.3274? What is σp′?

A sample of n = 64 scores has a mean of M = 68. Assuming that the population mean is p = 60, find the z-score for this sample: If it was obtained from a population with o = 16 Z = If it was obtained from a population with o = 32 Z = If it was obtained from a population with o = 48 Z =

Suppose that having a widow's peak was a dominant trait (W) compared to not having a widow's peak (w). In a sample size of 30 students, 15 were observed to have a widow's peak and 15 did not have a widow's peak. The expected frequency of a widow's peak is 75% chance of getting it and a 25% chance of not getting it. Perform a chi square analysis to see if the data above agrees with the predicted outcome.

12. Two independent samples are taken from two populations. Sample 1 has a mean of 12.8, a standard deviation of 2.3, and a sample size of 18. Sample 2 has a mean of 14.2, a standard deviation of 5.2, and a sample size of 23. This gives a standard error se(Ã1 — Ă2) = 1.212. A 95% confidence interval for the difference between the two means is: (A) (-2.00, -0.80). (B) (11.66, 13.94). (C) (-3.96, 1.16). (D) (-3.85, 1.05). (E) (-3.78, 0.98).

A random sample of n = 19 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that o1 = 10. For Englewood (a suburb of Denver), a random sample of n2 = 18 winter days gave a sample mean pollution index of x2 = 34. Previous studies show that o2 = 13. Assume the pollution index is normally distributed in both Englewood and Denver. Do these data indicate that the mean population pollution index of Englewood is different (either way) from that of Denver in the winter? Use a 1% level of significance. (a) What is the level of significance? State the null and alternate hypotheses. O Ho: H1 H2 O Ho: H1 = l2; H1: H1 < µ2 (b) What sampling distribution will you use? What assumptions are you making? O The standard normal. We assume that both population distributions are approximately normal with unknown standard deviations. O The Student's t. We assume that both population distributions are approximately normal with unknown standard deviations. O The Student's…

the data support the claim that the average ACT composite score of students from this students is randomly selected from a local high school with an X = 23 and s = 5.2. Do ACT composite scores are normally distributed with a u = 21. A sample of 25 students is randomly selected from a local high school with an X= 23 and s =5.L.D high school is different than 21 on the ACT composite score, using x = .05?