Let's go through each question step by step:
A. What is the distribution of X? X ~ N(mu, sigma^2)
- X represents the number of computers assembled per hour by a single worker.
- X follows a normal distribution with a mean (mu) of 4.6 computers per hour and a standard deviation (sigma) of 1 computer.
B. What is the distribution of T? T ~ N(mu_T, sigma_T^2)
- T represents the total number of computers assembled per hour by the 16 workers.
- The distribution of T is a normal distribution with a mean (mu_T) equal to the product of the number of workers (16) and the mean production rate per worker (4.6), and a standard deviation (sigma_T) equal to the product of the number of workers (16) and the standard deviation per worker (1).
C. What is the distribution of X^2? X^2 ~ chi-squared (pdf)
- X^2 represents the sum of squares of the deviations from the mean.
- X^2 follows a chi-squared distribution with degrees of freedom (df) equal to 1.
D. Probability that a randomly selected worker will put together between 4.5 and 4.6 computers per hour.
- To find this probability, we need to calculate the area under the normal distribution curve between the two values.
- Using a standard normal distribution table or a calculator, we can find the probabilities associated with the z-scores for 4.5 and 4.6 and subtract them to get the desired probability.
E. Probability that the average number of computers put together per hour by the 16 workers is between 4.5 and 4.6.
- The distribution of the sample mean (X-bar) for a large enough sample size (central limit theorem) is approximately normal.
- Calculate the mean (mu_X-bar) and standard deviation (sigma_X-bar) of the sample mean using the formulas:
mu_X-bar = mu
sigma_X-bar = sigma/sqrt (n), where n is the sample size (16 in this case).
- Then, calculate the z-scores for 4.5 and 4.6 using the formula:
z = (x - mu_X-bar) / sigma_X-bar
- Finally, use the standard normal distribution table or a calculator to find the probabilities associated with the z-scores and subtract them to get the desired probability.
F. Probability that a 16-person shift will put together between 68.8 and 72 computers per hour.
- Similar to part E, calculate the mean (mu_T) and standard deviation (sigma_T) for the total number of computers produced by the 16 workers.
- Convert the given values of 68.8 and 72 to z-scores using the formula:
z = (x - mu_T) / sigma_T
- Use the standard normal distribution table or a calculator to find the probabilities associated with the z-scores and subtract them to get the desired probability.
G. Is the assumption of normality necessary for parts E and F?
- Yes, the assumption of normality is necessary for parts E and F because we are using the normal distribution and its properties to calculate probabilities.
H. The least total number of computers produced by a group that receives a sticker.
- To determine the least total number of computers produced by a group that receives a sticker (top 15% productivity), we need to find the z-score corresponding to the 85th percentile of the normal distribution.
- Using the standard normal distribution table or a calculator, find the z-score associated with the
85th percentile.
- Then, calculate the number of computers corresponding to that z-score using the formula:
x = z * sigma_T + mu_T
- Round the result to the nearest whole number to find the least total number of computers produced by a group that receives a sticker.