Find the estimated standard error for the sample mean for each of the following samples. (Use one decimal place)

n=4 with SS = 48
_______

n=6 with SS= 270
_________

n= 12 with SS= 132
________

Why do t distributions tend to be flatter and more spread out than the normal distribution is? The (denominator) (numerator) (product) I chose product??___ of the t statistic contains the (sample standard deviation)(population mean)(population standard deviation)__i chose sample standard deviation________, which is _(different)(unknown)(the same)__I chose different ?________for different samples. The z score uses the _(population standard deviation)(population size)(sample standard deviation)_i chose population standard deviation?______________which is __(the same)(different)(unknown)_i chose same?______for different samples, Therefore, the t statistic has __(greater)(equal)(less)___less?________variabilty.

use the distribution tool to find the t values that form the boundaries of the critical region for a two-tailed test with o= .05 for each of the following sample sizes. use three decimal places.
t distribution
degrees of freedom= 21

n=6
t= ±

n=12
t=±

n=24
t=±