I'm not sure if this was answered before but I will ask just in case, NO LINKS. Must all measures of center appear as a number in the set of data collected? A.
All the measures of central tendency have to be numbers in the set of data.

B.
All the measures of central tendency are never numbers in the set of data.

C.
The mean and median may or may not be in the set of data, but the mode is always in the set of data.

D.
The mean and mode may or may not be in the set of data, but the median is always in the set of data.

According to a research study, parents with young children slept 6.4 hours each night last year, on average. a random sample of 18 parents with young children was surveyed and the mean amount of time per night each parent slept was 6.8. this data has a sample standard deviation of 0.9. (assume that the scores are normally distributed.) researchers conduct a one-mean hypothesis at the 5% significance level, to test if the mean amount of time parents with young children sleep per night is greater than the mean amount of time last year. the null and alternative hypotheses are h0: μ=6.4 and ha: μ> 6.4, which is a right-tailed test. the test statistic is determined to be t0=1.89 using the partial t-table below, determine the critical value(s). if there is only one critical value, leave the second answer box blank.