What must be considered when determining the critical t-value for a paired t-test? Select all that apply. 1. significance level

2. test statistic

3. number of population groups

4. degree of freedom

5. standard error of the mean

The weekly amount spent by a company for travel has an approximately normal distribution with mean = $550 and standard deviation = $40. a) what is the probability that the actual weekly expense will exceed $570 for more than 20 weeks during the next year? (note: one year = 52 weeks) b) what is the probability that actual weekly expenses exceed $580 for 10 or more, but 16 or fewer weeks during the next year?