In order to draw x ≤ -10 on a number line, first draw a closed dot at -10. This is because we have a ≤ and not a <. If we had a <, it would be an open dot.
Next, since we want x to be smaller, draw an arrow pointing towards all numbers that are smaller. This arrow would point to the left.
Solution: We are given:
Using the empirical rule, we have:
covers 68% of data.
Also the percentage of values below mean = Percentage of values above mean = 50%
Now, let's find the z score for x=20
Therefore, the percentage of values greater than 1 standard deviation above mean 
Expected number of students = 16% of 100 = 16
The cost of a single shot is
.78 +.52 +.96 = 2.26
they charge 25 a shot
25 - 2.26 = 22.74
there is a profit of 22.74 per shot
22.74 * 167 =3797.58
They make $3797.58
