Answer:
For this case we have the following info related to the time to prepare a return

And we select a sample size =49>30 and we are interested in determine the standard deviation for the sample mean. From the central limit theorem we know that the distribution for the sample mean
is given by:
And the standard deviation would be:

And the best answer would be
b. 2 minutes
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".
Solution to the problem
For this case we have the following info related to the time to prepare a return

And we select a sample size =49>30 and we are interested in determine the standard deviation for the sample mean. From the central limit theorem we know that the distribution for the sample mean
is given by:
And the standard deviation would be:

And the best answer would be
b. 2 minutes
Answer:
1.5/6
2.1/6
Step-by-step explanation:
If 1/4 of x is 16, we multiply 16 x 4 which will give us x=64. 3/4 of 64 = 48
Answer:
The confidence interval based on the paired design is wider because there is little variation in mileage between the cars.
Step-by-step explanation:
The sample size randomly collected is matched sample and since the confidence interval is based on the paired design is large and wide. There is small variation between the mileage of the two cars indicating the cars have mileage based on the fuel.