You can put this solution on YOUR website! Find the critical value(z alpha\2) needed to construct an 82% confidence interval
-----
82% centered on the mean leaves (100-82)/2 = 9% tails on the left and on the right.
-------
Left-tail z-value = invNorm(0.09)
Right-tail z-value = -invNorm(0.09)
Answer:: -invNorm(0.09) = 1.3408
-----------
Cheers,
Stan H.
--------------