Math Problem Statement

Suppose that the mean time someone spends using a device with a screen such as a smartphone, computer, or television is 8.35 hours. Use a normal probability distribution with a standard deviation of 1.9 hours to answer the following questions about daily screen time: a. What is the probability that a randomly selected person has between 3 and 8 hours of screen time a day? b. How many hours of screen time must a person have in order to be in the top 3% of all screen time values? c. What is the probability that a person has more than 5 hours of screen time a day?

Solution

The image contains a problem involving a normal distribution for daily screen time. Here's a breakdown of the key details:

  • Mean screen time (μ\mu) = 8.35 hours
  • Standard deviation (σ\sigma) = 1.9 hours
  • The questions involve finding probabilities and specific values related to the normal distribution.

Solutions:

a. Probability between 3 and 8 hours of screen time

  • The probability is given as 0.5395. This likely involves calculating the area under the normal curve between 3 and 8 hours using a Z-table or a calculator.

b. Hours of screen time to be in the top 3%

  • The required screen time is 16.18 hours. This corresponds to the 97th percentile of the distribution (top 3%).

c. Probability of more than 5 hours of screen time

  • The probability is 0.9099. This involves finding the area under the normal curve to the right of 5 hours.

Would you like a detailed explanation of any of these calculations or a step-by-step breakdown?

Here are 5 follow-up questions that could expand on this topic:

  1. How do you calculate the Z-score for a specific value in a normal distribution?
  2. What is the relationship between percentiles and Z-scores?
  3. How can the area under the normal curve be used to find probabilities?
  4. Why is it important to understand the concept of standard deviation in real-world contexts?
  5. How would the answers change if the standard deviation were larger or smaller?

Tip: When working with normal distributions, always remember to convert raw scores to Z-scores for easier probability lookup!

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Math Problem Analysis

Mathematical Concepts

Normal Distribution
Probability
Percentiles
Z-Scores

Formulas

Z = (X - μ) / σ
P(Z1 < Z < Z2)
P(X > X1)

Theorems

Empirical Rule
Properties of the Normal Distribution

Suitable Grade Level

Grades 11-12 (Advanced High School) or Introductory College Level