If we have a sample size of 15 and the population standard deviation is known, we will use: t- test for hypothesis testing z-test for hypothesis testing both t and z test F Test

Two Independent simple random samples are taken to test the difference between the means of two populations. The standard deviations are not known, but are assumed to be equal. The sample sizes are n1 = 15 and n2 = 35. The correct distribution to use is the t distribution with 51 degrees of freedom z distribution with 50 degrees of freedom z distribution with 49 degrees of freedom t distribution with 48 degrees of freedom

When is a t-test preferred over a z-test in statistical analysis?*1 pointWhen the sample size is smallWhen dealing with categorical dataWhen comparing three or more groupsWhen the population standard deviation is known

The t test for the difference between the means of two independent populationsalways assumes that the respectivea. sample sizes are equalb. sample variances are equalc. populations are normally distributed if each sample size is less than 30d. All of the above

ne-sample z-test using the given sample mean, population standard deviation, and sample size, with a significance level (alpha) of 0.10.

6.  A psychologist believes that it will take at least an hour for certain disturbed children to learn a task. To test this hypothesis, a random sample of 25 children will be used. What appropriate hypothesis test should be used for n = 25 and σ is unknown?*A. z-testB. t-testC. f-testD. r-test