A sample of n = 25 scores has a mean of x̅ = 65 and an estimated standard error of sx̅ = 2 points. What is the sample variance?

Calculate the observed z value using a sample mean of 25, a population average of 20, and a standard error of the mean of 8.

A phone service provider hypothesizes that Android users have a lower credit score rating than iPhone users and, if true, would like to build a marketing campaign around that idea. In order to test their hypothesis, they collect the data in the table below. Assume that credit scores are approximately normally distributed and that the variance in scores is the same between the two groups. What is the p- value of the test? Round your answer to three decimal places. Android Users Credit Scores 415 565 544 617 675 381 552 673 623 691 iPhone Users Credit Scores 631 659 549 681 632 596 695 673 685 653 535 593 710

Do men score lower on average compared to women on their statistics final exams?Final exam scores of 15 randomly selected male statistics students and 13 randomly selected female statistics students are shown below.Test the claim that men score lower on the statistics final exam than women do at the α = 0.025 level of significance. Assume variances are equal.     male female 94 92 76 82 75 74 74 62 78 86 85 78 72 75 85 85 65 79 79 73 93 76 78 93 64 84 69   82   Find Tc?