Math Problem Statement

A recent survey by the American Automobile Association showed that a family of two adults and two children on vacation in the United States will pay an average of $247 per day for food and lodging with a standard deviation of $60 per day. Assuming the data are normally distributed, find, to the nearest hundredth, the z-scores for each of the following vacation expense amounts. a. $197 per day.

b. $277 per day.

c. $310 per day.

Solution

To find the z-scores for the given vacation expense amounts, we can use the z-score formula:

z=xμσz = \frac{x - \mu}{\sigma}

Where:

  • xx is the value for which we are finding the z-score,
  • μ=247\mu = 247 is the mean (average expense per day),
  • σ=60\sigma = 60 is the standard deviation.

Let's calculate the z-scores for each of the given values:

a. For x=197x = 197:

z=19724760=5060=0.83z = \frac{197 - 247}{60} = \frac{-50}{60} = -0.83 The z-score for $197 per day is -0.83.

b. For x=277x = 277:

z=27724760=3060=0.50z = \frac{277 - 247}{60} = \frac{30}{60} = 0.50 The z-score for $277 per day is 0.50.

c. For x=310x = 310:

z=31024760=6360=1.05z = \frac{310 - 247}{60} = \frac{63}{60} = 1.05 The z-score for $310 per day is 1.05.

Summary:

  • a. $197 per day: z=0.83z = -0.83
  • b. $277 per day: z=0.50z = 0.50
  • c. $310 per day: z=1.05z = 1.05

Would you like further details or have any questions about these calculations?

Here are 5 related questions you could explore:

  1. What does a z-score of 0 represent in a normal distribution?
  2. How can we interpret negative z-scores in real-life scenarios?
  3. What is the probability of spending less than $197 per day?
  4. How would the z-scores change if the standard deviation was larger or smaller?
  5. How can we use z-scores to determine outliers in this data?

Tip: A z-score tells you how many standard deviations a data point is from the mean. It helps standardize different scales or data sets for comparison.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Z-Score

Formulas

Z-score formula: z = (x - μ) / σ

Theorems

68-95-99.7 rule for normal distribution

Suitable Grade Level

Grades 10-12