According to the latest financial reports from a sporting goods store, the mean sales per customer was $75 with a population standard deviation of $6. The store manager believes 39 randomly selected customers spent more per transaction.Use a calculator to find the probability that the sample mean of sales per customer is between $76 and $77 dollars. Round to two decimal places.
Q. According to the latest financial reports from a sporting goods store, the mean sales per customer was $75 with a population standard deviation of $6. The store manager believes 39 randomly selected customers spent more per transaction.Use a calculator to find the probability that the sample mean of sales per customer is between $76 and $77 dollars. Round to two decimal places.
Identify Given Values and Formula: Identify the given values and the formula to use.We are given:- Mean sales per customer μ = $75- Population standard deviation σ = $6- Sample size n = 39- We want to find the probability that the sample mean xˉ is between $76 and $77.We will use the z-score formula for the sample mean:z=σ/nxˉ−μWe will calculate two z-scores, one for $76 and one for $77, and then use the standard normal distribution to find the probabilities.
Calculate Z-Score for $76: Calculate the z-score for $76. Using the z-score formula: z=6/3976−75 First, calculate the denominator σ/n: σ/n=396≈6.2456≈0.961 Now, calculate the z-score: z=0.96176−75≈0.9611≈1.041
Calculate Z-Score for $77: Calculate the z-score for $77. Using the z-score formula: z=6/3977−75 We already calculated the denominator σ/n in the previous step, so we can use it again: z=0.96177−75≈0.9612≈2.081
Use Standard Normal Distribution: Use the standard normal distribution to find the probability for each z-score.We need to find the probability that z is less than 1.041 and then the probability that z is less than 2.081. The difference between these two probabilities will give us the probability that the sample mean is between $76 and $77.Using a standard normal distribution table or calculator:P(z < 1.041) \approx 0.851P(z < 2.081) \approx 0.981
Calculate Probability: Calculate the probability that the sample mean is between $76 and $77. We subtract the probability of z being less than 1.041 from the probability of z being less than 2.081: Probability = P(z < 2.081) - P(z < 1.041) Probability ≈0.981−0.851 Probability ≈0.130
More problems from Find probabilities using the binomial distribution