Math Problem Statement

The mean production of workers in a certain factory is 10 products per hour, with a standard deviation of 1.5 products per hour. What is the probability of finishing (a) less than 12.8 product per hour? (b) more than 12 products per hour?

Solution

This problem involves finding probabilities related to a normal distribution. The given information is:

  • Mean (μ\mu) = 10 products per hour
  • Standard deviation (σ\sigma) = 1.5 products per hour

We assume the production follows a normal distribution. To solve for the probabilities, we will use the standard normal distribution ZZ-scores.

The formula for the ZZ-score is:

Z=XμσZ = \frac{X - \mu}{\sigma}

where:

  • XX is the value of interest,
  • μ\mu is the mean,
  • σ\sigma is the standard deviation.

(a) Probability of producing less than 12.8 products per hour

We need to find P(X<12.8)P(X < 12.8).

  1. First, compute the ZZ-score for X=12.8X = 12.8: Z=12.8101.5=2.81.51.87Z = \frac{12.8 - 10}{1.5} = \frac{2.8}{1.5} \approx 1.87

  2. Now, we find the probability corresponding to Z=1.87Z = 1.87. Using a standard normal table, the cumulative probability for Z=1.87Z = 1.87 is approximately 0.9693.

Therefore, the probability of producing less than 12.8 products per hour is:

P(X<12.8)0.9693P(X < 12.8) \approx 0.9693

(b) Probability of producing more than 12 products per hour

We need to find P(X>12)P(X > 12).

  1. First, compute the ZZ-score for X=12X = 12: Z=12101.5=21.51.33Z = \frac{12 - 10}{1.5} = \frac{2}{1.5} \approx 1.33

  2. Now, we find the cumulative probability for Z=1.33Z = 1.33 from the standard normal table, which is approximately 0.9082. Since we want the probability for X>12X > 12, we subtract this value from 1:

P(X>12)=10.9082=0.0918P(X > 12) = 1 - 0.9082 = 0.0918

Therefore, the probability of producing more than 12 products per hour is:

P(X>12)0.0918P(X > 12) \approx 0.0918

Summary:

  • (a) P(X<12.8)0.9693P(X < 12.8) \approx 0.9693
  • (b) P(X>12)0.0918P(X > 12) \approx 0.0918

Would you like to see the details of these calculations, or any further clarification?


Here are 5 related questions to expand your understanding:

  1. How do we interpret the ZZ-score in a normal distribution?
  2. What is the probability of producing between 9 and 12 products per hour?
  3. How would the probabilities change if the standard deviation increased to 2?
  4. Can we calculate the probability of producing exactly 10 products per hour?
  5. How do we apply the concept of the central limit theorem to production rates?

Tip: Always visualize normal distribution problems using a bell curve to better understand areas under the curve and probabilities.

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Math Problem Analysis

Mathematical Concepts

Normal Distribution
Probability
Z-scores

Formulas

Z = (X - μ) / σ

Theorems

Properties of the Standard Normal Distribution

Suitable Grade Level

Grades 10-12