I need help with the picture and the questions below :

A bank wonders whether omitting the annual credit card fee for customers who charge at least $3,000 in a year would increase the

Law Incorporation [45]

Answer:

The 95% confidence interval for the mean amount of the increase is ($541.6, $588.4). This means that we are 95% sure that the mean amount of increase of all customers who charge at least $3,000 in a year is between these two values.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

$M = 1.96\frac{267}{\sqrt{500}} = 23.4$

The lower end of the interval is the sample mean subtracted by M. So it is 565 - 23.4 = $541.6

The upper end of the interval is the sample mean added to M. So it is 565 + 23.4 = $588.4

The 95% confidence interval for the mean amount of the increase is ($541.6, $588.4). This means that we are 95% sure that the mean amount of increase of all customers who charge at least $3,000 in a year is between these two values.

4 0

3 years ago

A city police force is made up of 24% females. If there are 72 females on the force, how many males are on the force?

erastovalidia [21]

Answer:

228 males

Step-by-step explanation:

Let x be the number of males.

This means x + 72 is the total number of people.

So $\frac{72}{x+72}$ is the fraction of females in the force.