Question

What is the probability that two randomly chosen players completed the walk in 2.9 hours or more? Show your work.

Answer 1

Answer:

8.08%

Step-by-step explanation:

Suppose several high schools in a city are sponsoring a walk-athon to raise money for a local charity. A certain route is mapped out through the city and each participant finds sponsors to donate money for the walk. If a participant completes the walk under a certain time, extra money will be donated. You are responsible for recording the finishing times for each of the participants. After collecting all of the data, you determine that the finishing times are normally distributed with a mean of 2.6 hours and a standard deviation of 0.3 hour.

Answer:

Given that:

Mean (μ) = 2.6 hours and standard deviation (σ) = 0.3 hour, n = 2

The z score is used in statistics to determine the amount of standard deviation by which the raw score is above or below the mean. It is given by the equation:

$z=\frac{x-\mu}{\sigma}$, where x is the raw score.

If the sample size (n) is taken then the z score is given by:

$z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n} } }$

Therefore for this problem the z score is:

$z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n} } }=\frac{2.9-2.6}{\frac{0.3}{\sqrt{2} } }=1.41$

From the normal distribution table, probability that two randomly chosen players completed the walk in 2.9 hours or more = P(x > 2.9) = P(z > 1.41) = 1 - P(z < 1.41) = 1 - 0.9192 = 0.0808 = 8.08%