For large numbers of degrees of freedom, the critical χ2 values can be approximated as follows: χ2 = 12
(z + 2k - 1 )2,
where k is the number of degrees of freedom and z is the critical value. To find the lower critical
value, the negative z-value is used, to find the upper critical value, the positive z-value is used.
Use this approximation to estimate the critical value of χ2 in a right-tailed hypothesis test with
n = 143 and α = 0.01.