Question

In a study on the physical activity of people, researchers measured overall physical activity as the total number of registered movements (counts) over a period of time and then computed the number of counts per minute (cpm) for each subject. The study revealed that the overall physical activity of obese people has a mean of μ=322cpm and a standard deviation σ=92cpm. In a random sample of 100 obese people, consider x ̅, the sample mean counts per minute.

1)

Which of the following best describes the sampling distribution for X ̅ (X bar)?

10/10 Points

• X ̅ ~ N(312, 10)

• X ̅ ~ N(31200, 94)

• X ̅ ~ N(312, 9.4)

• X ̅ ~ N(312, 94)

• X ̅ ~ N(31200, 9.4)

2)

Find the probability that the mean overall physical activity level of the sample is between 310 and 340 cpm.

10/10 Points

• 83.4%

• 12.9%

• not enough information

• 87.9%

• 12.1%

3)

What is the z-score for a sample mean of 305?

0/10 Points

• 1.8

• -0.18

• -1.7

• -0.17

4)

Find the 90th percentile counts per minute in a sample of 100 young adults.

10/10 Points

• 439.9 cpm

• 310.2 cpm

• 333.8 cpm

• 335 cpm

5)

Suppose we are interested in the activity of one individual with a cpm distribution that is approximately normal. Find the z-score of a person with 305 cpm.

0/10 Points

• -2.1

• -0.17

• -1.7

• -1.8

6)

Which of the following statements best describes the difference between the answer to #3 and #5?

0/10 Points

• The z-score for the an individual is greater than that of a sample mean because the distribution for an individual is more spread out (large standard deviation).

• The z-score for the an individual is the same than that of a sample mean because they both involve 305 cpm and a normal distribution.

• The z-score for the an individual is the same than that of a sample mean because the distributions are both normal with the same mean.

• The z-score for the an individual is less than that of a sample mean because the distribution for an individual is less spread out (small standard deviation).

7)

Now suppose we are interested in the total activity (Σcpm) of a random sample of 25 obese people. Answer the following questions on a separate sheet of paper and upload to "Quiz Ch. 7 Free Response Answer":

a) Write a distribution statement that describes this new study of total activity (Σcpm).

b) Find the probability that the total cpm for 25 obese people is less than 7,500 cpm.

c) Sketch the graph, labeling and scaling the horizontal axis. Shade the region corresponding to the probability in part b.

d) How likely is it that those 25 people will collectively register more than 9,000 cpm? Explain how you came to that conclusion.

(it is 322, but the given answers are wrong, I need to show work any way)

Answer 1

according to HomeworkLib guideline we can answer only first four parts please ask another with another question