Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 2: Q 5. (page 104)

Setting speed limits According to the Los Angeles Times, speed limits on California highways are set at the 85th percentile of vehicle speeds on those stretches of road. Explain to someone who knows little statistics what that means.

Short Answer

Expert verified

15% of the data is greater than or equal to the data point. The speed limits are established at the speed at which 85 percent of vehicle speeds are below the speed limit.

Step by step solution

01

Part (a) Step 1: Given information

On California highways, vehicle speed limits are established at the 85th percentile for specific lengths of road.

02

Concept

The percentile of an individual is the percentage of the distribution that is less than the data value of the individual.

03

Explanation

The 85th percentile is a data point in which 85 percent of the data is less than or equal to the data point, and 15% of the data is higher than or equal to the data point. On some stretches of road, the speed limits are established at the speed at which 85 percent of vehicle speeds are below the speed limit.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Batter up! In baseball, a player’s batting average is the proportion of times the player gets a hit out of his total number of times at-bat. The distribution of batting averages in a recent season for Major League Baseball players with at least 100 plate appearances can be modeled by a Normal distribution with mean μ=0.261 and standard deviation σ=0.034Sketch the Normal density curve. Label the mean and the points that are 1,2, and 3 standard deviations from the mean.

The army reports that the distribution of head circumference among male soldiers is approximately Normal with mean of 22.8inches and standard deviation 1.1inches.

(a) A male soldier whose head circumference is 23.9-inches would be at what percentile? Show your method clearly.

(b) The army’s helmet supplier regularly stocks helmets that fit male soldiers with head circumferences between 20and 26inches. Anyone with a head circumference outside that interval requires a customized helmet order. What percent of male soldiers require custom helmets? Show your work, including a well-labeled sketch of a Normal curve.

(c) Find the interquartile range for the distribution of head circumference among male soldiers. Show your method clearly.

Cool pool? Coach Ferguson uses a thermometer to measure the temperature

(in degrees Fahrenheit) at 20different locations in the school swimming pool. An analysis of the data yields a mean of 77°Fand a standard deviation of 3°F(Recall that°C=59°F−1609

a. Find the mean temperature reading in degrees Celsius.

b. Calculate the standard deviation of the temperature readings in degrees Celsius.

Carbon dioxide emissions The following figure is a Normal probability plot of the emissions of carbon dioxide CO2 per person in 48 countries.15 Use the graph to determine if this distribution of CO2 emissions is approximately Normal.

Shoes Refer to Exercise 1. Jackson, who reported owning 22 pairs of shoes, has a standardized score of z=1.10.

a. Interpret this z-score.

b. The standard deviation of the distribution of the number of pairs of shoes owned in this sample of 20 boys is 9.42. Use this information along with Jackson’s z-score to find the mean of the distribution.
See all solutions

Recommended explanations on Math Textbooks

Theoretical and Mathematical Physics

Read Explanation

Decision Maths

Read Explanation

Pure Maths

Read Explanation

Applied Mathematics

Read Explanation

Statistics

Read Explanation

Mechanics Maths

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free