N 1
Part a
68%
Divide by 2
68%/2=34%=34/100=0.34
using a z-score tables
we have that
z=0.994
N 2
50%
50%/2=25%=25/100=0.25
z=0.674
N 3
80%
80%/2=40%=40/100=0.40
z=1.282
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