Statistics Practice questions

[01] Consider the following numbers:

Sue says the average of the numbers is 3.5. When she says 'average', she is giving the

[02] Alan surveys the citizens of Townville by calling every 50^th name in the phone book. This is an example of what kind of sample?

[03] Every time Sam wears his red shirt, it rains outside. This is an example of

[04] Find Q₁ for the following sample. Round your answer to 2 decimal places.

[05] If two dice are rolled one time, find the probability that the sum is not 10. Round your answer to 3 decimal places.

[06] If a coin is flipped 4 times in a row, find the probability that there will be heads at least once. Round your answer to 4 decimal places.

[07] Find the sample standard deviation of the sample below. Round your answer to 3 decimal places.

[08] A sample has a mean of 5.3, a median of 5.1, a sample standard deviation of 1.2, and a sample variance of 1.44. Compute the z score for x=7.2. Round your answer to 3 decimal places.

[09] Suppose we want to estimate the mean body temperature of a population. If we know that the population standard deviation is 1.6°C and we want to be 95% certain we have correctly estimated the mean body temperature to within ±0.5°C, how large a sample size do we need to randomly select? Round your answer up to a whole number of people.

[10] Fifteen students are competing in a spelling bee. The top 3 students (in any order) will advance to the state competition. How many 3-student combinations are possible?

[11] If two cards are drawn without replacement, what is the probability that the first card is a black card and the second card is a red card? Round your answer to 4 decimal places.

[12] If a fair die is rolled two times, find the probability of rolling a 3, and then a 4. Round your answer to 4 decimal places.

[13] A random sample of 45 students studied for a mean duration of 6.8 hours last week. If the population standard deviation is 1.2 hours, what is the 99% confidence interval for the population mean?

[14] Data from 1963 shows that the standard deviation of daily high temperatures in Cititon was 5.5°C. A recent study of 22 randomly chosen days had a standard deviation of high temperature of 7.5°C. At a significance of 0.05, does it appear that the standard deviation has increased?

[15] Consider the following data:

What is the correlation coefficient? Round your answer to 4 decimal places.

[16] Consider the following data:

Find the slope b in the regression equation y=a+bx. Round your answer to 4 decimal places.