Sophia Introduction to Statistics Unit 5 Milestone 5

Recall that we have n = 7, so the df = n-1 = 6. So if we go to the row where df = 7 and then 0.025 for the tail probability, this gives us a value of 2.447 or 2.45. Recall that a 95% confidence interval would have 5% for the tails, so 2.5% for each tail. We can also use the last row and find the corresponding confidence level (see 95%). CONCEPT How to Find a Critical T Value 5 A market research company conducted a survey of two groups of students from different schools. They found that students from school A spent an average of 90 minutes studying daily, while the students from school B spent an average of 75 minutes daily. They want to find out if the difference in the mean times spent studying by the students of the two schools is statistically significant. Which of the following sets shows the correct null hypothesis and alternative hypothesis? Null Hypothesis: The difference in the mean times spent by the schools' students is 15 minutes. Alternative Hypothesis: There is no difference in the mean times spent by the schools' students. Null Hypothesis: There is at least some difference in the mean times spent by the schools' students. Alternative Hypothesis: The students from school B spend more time studying than the students from school A. Null Hypothesis: There is no difference in the mean times spent by the schools' students. Alternative Hypothesis: There is at least some difference in the mean times spent by the schools' students. Null Hypothesis: School B students spend more time studying than School A. Alternative Hypothesis: The difference in the mean times spent by the schools' students is 15 minutes. RATIONALE Recall that the null hypothesis is always of no difference. So the null hypothesis (Ho) is that the mean time studying for group A = mean for group B. This would indicate no difference between the two groups. The alternative hypothesis (Ha) is that there is difference in the mean study time between the two groups. CONCEPT 7/2/2020 Sophia :: Welcome Hypothesis Testing 6 Carl recorded the number of customers who visited his new store during the week: Day Customers Monday 17 Tuesday 13 Wednesday 14 Thursday 16 He expected to have 15 customers each day. To answer whether the number of customers follows a uniform distribution, a chi-square test for goodness of fit should be performed. (alpha = 0.10) What is the chi-squared test statistic?