# Question

According to The Earth: Structure, Composition and Evolution (The Open University, S237), for earthquakes with a magnitude of 7.5 or greater on the Richter scale, the time between successive earthquakes has a mean of 437 days and a standard deviation of 399 days. Suppose that you observe a sample of four times between successive earthquakes that have a magnitute of 7.5 or greater on the Richter scale.

a. On average, what would you expect to be the mean of the four times?

b. How much variation would you expect from your answer in part (a)? (Hint: Use the three-standard-deviations rule.)

a. On average, what would you expect to be the mean of the four times?

b. How much variation would you expect from your answer in part (a)? (Hint: Use the three-standard-deviations rule.)

## Answer to relevant Questions

The U.S. Department of Health and Human Services publishes information on AIDS in Morbidity and Mortality Weekly Report. During one year, the number of provisional cases of AIDS for each of the 50 states are as presented on ...Consider simple random samples of size n without replacement from a population of size N. a. Show that if n ≤ 0.05N, then b. Use part (a) to explain why there is little difference in the values provided by Equations (7.1) ...A variable of a population has a mean of μ = 35 and a standard deviation of σ = 42. a. If the variable is normally distributed, identify the sampling distribution of the sample mean for samples of size 9. b. Can you answer ...Data on salaries in the public school system are published annually in National Survey of Salaries and Wages in Public Schools by the Education Research Service. The mean annual salary of (public) classroom teachers is $49.0 ...Population data: 2, 3, 5, 7, 8. a. Find the mean, μ, of the variable. b. For each of the possible sample sizes, construct a table similar to Table 7.2 on page 281 and draw a dotplot for the sampling distribution of the ...Post your question

0