<h3><u>Question:</u></h3>
Aubrey's dinner cost $85 . She tips the waitstaff 30% for excellent service. How much does Aubrey tip the waitstaff?
<h3><u>Answer:</u></h3>
Aubrey paid $ 25.5 to the wait staff
<h3><u>Solution:</u></h3>
Given that, Aubrey's dinner cost $ 85
She tips the waitstaff 30% for excellent service
We have to find the amount paid as tip to wait staff
Cost = $ 85
Tip = 30 %
So the tip amount paid is 30 % of 85
<h3><u>Find out 30 % of 85</u></h3>

Thus Aubrey paid $ 25.5 to waitstaff
Approximately 1718 have a score within that range.
We calculate the z-score for each end of this spectrum:
z = (X-μ)/σ = (2.5-3.1)/0.3 = -0.6/0.3 = -2
Using a z-table (http://www.z-table.com) we see that the area to the left of, less than, this z-score is 0.0228.
For the upper end:
z = (3.7-3.1)/0.3 = 0.6/0.3 = 2
Using a z-table, we see that the area to the left of, less than, this z-score is 0.9772.
The probability between these is given by subtracting these:
0.9772 - 0.0228 = 0.9544.
This means the proportion of people that should fall between these is 0.9544:
0.9544*1800 = 1717.92 ≈ 1718