The U. S. Department of Housing and Urban Development publishes data on the fair market monthly rent for existing one-bedroom housing by metropolitan area (The Federal Register, April 30 1997). The standard deviation for the monthly rent is about $80. Assume that a sample of metropolitan areas will be selected in order to estimate the population mean of the monthly rent for existing one-bedroom housing. Use 95% confidence. a. How large should the sample be if the desired margin of error is $25?

So the answer for this case would be n=247 rounded up to the nearest integer

Step-by-step explanation:

We know that the standard deviation is :

represent the deviation

The margin of error is given by this formula:

   (a)

And on this case we have that ME =25 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

  (b)

The critical value for 95% of confidence interval now can be founded using the normal distribution and the critical value would be , replacing into formula (b) we got:

So the answer for this case would be n=247 rounded up to the nearest integer

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."

step-by-step explanation: