# Question: Refer to Exercise 13 35 which discussed a study on the

Refer to Exercise 13.35, which discussed a study on the effects of cloud seeding to produce rainfall. Some researchers think that cloud seeding has little effect on "low rain potential" clouds. Instead, they claim, most of the action is with clouds that would produce lots of rain even without seeding. In this scenario, clouds that would produce little rain without seeding will produce little rain with seeding. However, the clouds that would produce the most rain without seeding will produce much, much more rain with cloud seeding. To test this, researchers carried out a randomization test to find out whether the third quartile of rainfall increased under cloud seeding. The table gives summary statistics.

a. Explain what it means to say that the third quartile of rainfall is 474.30 acre-feet.

b. Why is the third quartile an appropriate statistic to answer the researchers' question?

c. What is the observed difference in third-quartile rainfall between the seeded and unseeded clouds?

d. To determine whether such differences could occur by chance, a statistician could have written the 52 rainfall amounts on separate slips of paper and randomly dealt them into two stacks. He or she would then have computed the third quartile of each stack and found the difference. A computer actually did this 1000 times, each time finding the difference between the third quartile for the seeded clouds minus the third quartile for the unseeded clouds. The results are shown in the histogram. Referring to the histogram, carry out a hypothesis test to test whether cloud seeding increased the third-quartile rainfall. (You will have to get approximate p-values by reading the histogram.) (Remember that you need only decide whether the p-value is larger or smaller than 0.05.)

a. Explain what it means to say that the third quartile of rainfall is 474.30 acre-feet.

b. Why is the third quartile an appropriate statistic to answer the researchers' question?

c. What is the observed difference in third-quartile rainfall between the seeded and unseeded clouds?

d. To determine whether such differences could occur by chance, a statistician could have written the 52 rainfall amounts on separate slips of paper and randomly dealt them into two stacks. He or she would then have computed the third quartile of each stack and found the difference. A computer actually did this 1000 times, each time finding the difference between the third quartile for the seeded clouds minus the third quartile for the unseeded clouds. The results are shown in the histogram. Referring to the histogram, carry out a hypothesis test to test whether cloud seeding increased the third-quartile rainfall. (You will have to get approximate p-values by reading the histogram.) (Remember that you need only decide whether the p-value is larger or smaller than 0.05.)

**View Solution:**## Answer to relevant Questions

McDonald's claims that its ice cream cones typically weigh 3.18 ounces (converted from grams). Here are the weights, in ounces, of cones purchased on different days from different servers: 4.2, 3.6, 3.9, 3.4, and 3.3 Carry ...Determine whether the median number of texts sent and the median number received for all StatCrunch users are different at the 0.05 level by using a sign test. Log Transforms a. Find the log (base 10) of each number: 10, 100, 1000, 4500 b. The following numbers are in log units. Do the back transformation by finding the antilog (base 10) of each number: 2, 3, 2.5 5.84 A random sample of 29 community college students were asked their height in inches and the height of their biological parent of the same gender. The output of a regression analysis for predicting student height from parent ...Data were collected showing the gestation period (in days) and the average longevity (in years) for 32 animals. Assume that all conditions of the linear regression model hold. The data are available on this text's website ...Post your question