Math Problem Statement
The weights of a certain dog breed are approximately normally distributed with a mean of 52 pounds, and a standard deviation of 6.6 pounds. Use your graphing calculator to answer the following questions. Write your answers in percent form. Round your answers to the nearest tenth of a percent.
a) Find the percentage of dogs of this breed that weigh less than 52 pounds. % b) Find the percentage of dogs of this breed that weigh less than 50 pounds. % c) Find the percentage of dogs of this breed that weigh more than 50 pounds. %
Solution
Given that the weights of this dog breed are approximately normally distributed with a mean (μ) = 52 pounds and a standard deviation (σ) = 6.6 pounds, we can answer these questions by using the standard normal distribution (also called the Z-distribution).
We'll calculate the Z-scores for the values, which tells us how many standard deviations away a given value is from the mean. The Z-score is given by the formula:
Once we have the Z-scores, we can use standard normal distribution tables (or a graphing calculator) to find the corresponding percentages.
a) Find the percentage of dogs that weigh less than 52 pounds:
Since 52 pounds is the mean, the Z-score for 52 pounds is:
From the Z-table (or calculator), a Z-score of 0 corresponds to 50%. So, 50% of the dogs weigh less than 52 pounds.
b) Find the percentage of dogs that weigh less than 50 pounds:
Now, for X = 50 pounds, the Z-score is:
Using a Z-table or calculator, a Z-score of -0.303 gives a cumulative probability of approximately 38.1%. So, 38.1% of the dogs weigh less than 50 pounds.
c) Find the percentage of dogs that weigh more than 50 pounds:
To find the percentage of dogs weighing more than 50 pounds, we subtract the cumulative probability for 50 pounds from 100%:
Thus, 61.9% of the dogs weigh more than 50 pounds.
Let me know if you need further clarifications!
Here are some related questions:
- What percentage of dogs weigh more than 52 pounds?
- How would the results change if the standard deviation were 5 pounds?
- What is the weight corresponding to the 90th percentile for this dog breed?
- How can you calculate the percentage of dogs weighing between 50 and 55 pounds?
- If the weight of a dog is 60 pounds, what is its Z-score?
Tip: Always check the Z-score table for exact values when approximating percentages from Z-scores!
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Math Problem Analysis
Mathematical Concepts
Statistics
Normal Distribution
Z-Scores
Formulas
Z-score formula: Z = (X - μ) / σ
Theorems
Empirical Rule (68-95-99.7 Rule)
Suitable Grade Level
Grades 9-12
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