A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 10 days following no advertisements, the mean was 23.6 purchasing customers with a standard deviation of 0.9 customers. On 11 days following advertising, the mean was 24.9 purchasing customers with a standard deviation of 1.5 customers. Test the claim, at the 0.10 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 3 of 3 : Draw a conclusion and interpret the decision.

Laura es una gerente de inventarios que quiere evaluar la precisión de su modelo de pronóstico para la demanda semanal de un producto. Para ello, calcula el Error Porcentual Absoluto Medio (MAPE) de los pronósticos realizad durante las últimas cinco semanas. Los valores reales y los valores pronosticados de la demanda (en unidades) son siguientes:

simple random sample of size \( n \) is drawn from a population that is normally distributed. The sample mean, \( \overline{\mathrm{x}} \), is found to be 105 , and the sample standard deviation, \( s \), is found to be 10 . Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 16 . How does decreasing the sample size affect the margin of error, E? ) Construct an \( 80 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . Compare the results to those obtained in part (a). How does decreasing the level of confidence affect the size of the margin d) Could we have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed? Lower bound: \( \square \); Upper bound: (Use ascending order. Round to one decimal place as needed.)

Determine the point estimate of the population mean and margin of error for the confidence interval. Lower bound is 16, upper bound is 28 . The point estimate of the population mean is

Question 6 of 7 , Step 2 of 3 It currently takes users a mean of 22 minut made to the program, the company execut simple random sample of 91 new custome deviation of 5.5 minutes. Perform a hypoth Step 2 of 3 : Compute the value of the test Answer

A simple random sample of size \( n \) is drawn from a population that is normally distributed. The sample mean, \( \dot{x} \) is found to be 105 , and the sample standard dev (a) Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . (b) Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 16 . How does decreasing the sample size affect the margin of error, E? (c) Construct an \( 80 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . Compare the results to those obtained in part (a). How does decreasing the level 0 (d) Could we have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed? (a) Construct a \( 95 \% \) confidence interval about \( \mu \) if the sample size, \( n \), is 20 . Lower bound: \( \square \); Upper bound: (Use ascending order. Round to one decimal place as needed.)