Use the information in Example 6.10 to answer the following questions. Quiz
The question sheet
Reveal any answer as you study-
For smartphone users ages 13 to 55+, the ages approximately follow which distribution?
- Uniform
- Normal
- Binomial
- Exponential
Reveal answer
Answer: Normal
Source evidence
PDF page 385: In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36.9 years and 13.9 years respectively. Using this information, answer the following questions (round answers to one decimal place).
-
What is the approximate mean age of smartphone users in the given data?
- 46.3 years
- 40.4 years
- 27.5 years
- 36.9 years
Reveal answer
Answer: 36.9 years
Source evidence
PDF page 385: In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36.9 years and 13.9 years respectively. Using this information, answer the following questions (round answers to one decimal place).
-
What is the approximate standard deviation of smartphone users' ages?
- 36.9 years
- 13.9 years
- 27.5 years
- 18.8 years
Reveal answer
Answer: 13.9 years
Source evidence
PDF page 385: In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36.9 years and 13.9 years respectively. Using this information, answer the following questions (round answers to one decimal place).
-
To how many decimal places should the answers be rounded?
- Two
- Zero
- Three
- One
Reveal answer
Answer: One
Source evidence
PDF page 385: In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36.9 years and 13.9 years respectively. Using this information, answer the following questions (round answers to one decimal place).
-
Q3 corresponds to which percentile?
- 90th percentile
- 25th percentile
- 50th percentile
- 75th percentile
Reveal answer
Answer: 75th percentile
Source evidence
PDF page 385: Calculate Q3 = 75 percentile and Q1 = 25 percentile.
-
Q1 corresponds to which percentile?
- 30th percentile
- 40th percentile
- 25th percentile
- 75th percentile
Reveal answer
Answer: 25th percentile
Source evidence
PDF page 385: Calculate Q3 = 75 percentile and Q1 = 25 percentile.
-
What is the value of Q3, the 75th percentile?
- 40.4215
- 46.2754
- 36.9
- 27.5246
Reveal answer
Answer: 46.2754
Source evidence
PDF page 385: invNorm(0.75,36.9,13.9) = Q3 = 46.2754
-
What is the value of Q1, the 25th percentile?
- 18.8
- 40.4215
- 46.2754
- 27.5246
Reveal answer
Answer: 27.5246
Source evidence
PDF page 385: invNorm(0.25,36.9,13.9) = Q1 = 27.5246
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In part b, forty percent of the ages are at least what age?
- 46.3 years
- 40.4 years
- 36.9 years
- 27.5 years
Reveal answer
Answer: 40.4 years
Source evidence
PDF page 385: The area to the left of k = 0.60. invNorm(0.60,36.9,13.9) = 40.4215. k = 40.4. Forty percent of the ages that range from 13 to 55+ are at least 40.4 years.
-
The phrase 'at least' translates to which inequality?
- Less than or equal to
- Less than
- Greater than or equal to
- Equal to
Reveal answer
Answer: Greater than or equal to
Source evidence
PDF page 385: Solution 6.11 b. Find k where P(x ≥ k) = 0.40 ("At least" translates to "greater than or equal to.") 0.40 = the area to the right.
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For P(x ≥ k) = 0.40, the area to the left of k equals what?
- 0.40
- 0.75
- 0.60
- 0.25
Reveal answer
Answer: 0.60
Source evidence
PDF page 385: Area to the left = 1 – 0.40 = 0.60.
PDF page 385: The area to the left of k = 0.60. invNorm(0.60,36.9,13.9) = 40.4215. k = 40.4. Forty percent of the ages that range from 13 to 55+ are at least 40.4 years.
-
Which calculator command was used to find Q3?
- normalcdf
- tcdf
- binompdf
- invNorm
Reveal answer
Answer: invNorm
Source evidence
PDF page 385: invNorm(0.75,36.9,13.9) = Q3 = 46.2754
Introductory Statistics
Introductory Statistics by OpenStax, used under CC BY 4.0. Changes made by Stratacademy.
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