1) Let's begin with finding the Z-score for this.
a) X> 140
Now, that we have found this Z-score we need to resort to the Z-table:
This is equivalent to saying that 0.38% of this population are taken to be genius.
b) Very superior intelligence 120
Since we know the Z-score for 140 let's find the Z-score for 120
[tex]\begin{gathered} Z=\frac{120-100}{15}=1.33 \\ \\ P(120So we can tell that approximately
8.8% are taken to possess very superior intelligence.
c) Normal 90
[tex]\begin{gathered} Z=\frac{90-100}{15}=-0.67 \\ \\ Z=\frac{109-100}{15}=0.6 \\ \\ P(-0.67