1. More Normal Distribution Practice!
Unit 2 Day 3
More Normal Distribution Practice!

2. Practice 1
On the driving range, Tiger Woods practices his swing with a particular club by hitting many, many balls. When Tiger hits his driver, the distance the ball travels follows a Normal distribution with mean 304 yards and standard deviation 8 yards. What percent of Tiger’s drives travel at least 290 yards?

3. STATE Express the problem in terms of the observed value x.
Your answer should be similar to this:
Let x = distance that Tiger’s ball travels. The variable x has a Normal distribution with μ = 304 and σ = 8. We want the proportion of Tiger’s drives with x ≥ 290.

4. PLAN
Draw a picture of the distribution and shade the area of interest under the curve.
Your answer should be similar to this:

5. DO Perform calculations. Your answer should be similar to this:
Standardize x to restate the problem in terms of a standard Normal variable z.
Use Table A and the fact that the total area under the curve is 1 to find the required area under the standard Normal curve
Your answer should be similar to this:
To standardize for x=290, we have
So x ≥ 290 corresponds to z ≥ under the standard Normal curve.
Using Table A, we see that the proportion of observations less than is About 4% of Tiger’s drives travel less than 290 yards. The area to the right of is therefore 1 – = This is about 0.96, or 96%

6. CONCLUDE Write your conclusion in context of the problem.
Your answer should be similar to this:
About 96% of Tiger Wood’s drives on the range travel at least 290 yards.

7. Practice 2
What percent of Tiger’s drives travel between 305 and 325 yards?
(State, Plan, Do, Conclude)