Q1) Tables illustrate that 95% critical values for some t distributions are (to 2 dp) as follows:

df 6 9 12 20 30 critical values ±2.45 ±2.26 ±2.18 ±2.09 ±2.04

Use statistical tables or TINV function in excel to find critical values for the t distribution with following degrees of freedom 5 8 15 18 24 60 120.  Combine two tables, and therefore argue that these critical values approach ±1.96 as number of degrees of freedom tends to infinity. Briefly explain on why would we must expect ±1.96 to be the limit here. Examine the behaviour of 99% critical values for these degrees of freedom, and comment on the limits in this case.