A public radio station held a fund-raiser. The table below summarizes the donor category and method of donation.
Donor Category | |||
---|---|---|---|
Supporter | Patron | ||
Method of | Phone calls | 400 | 672 |
Donation | Online | 1200 | 2016 |
To the nearest thousandth, find the probability that a randomly selected donor was categorized as a supporter, given that the donation was made online.
Do these data indicate that being a supporter is independent of donating online? Justify your answer.
Calculate the probability of being a supporter given the donation was made online.
Determine if being a supporter is independent of donating online.
In watching auditions for lead singer in a band, Liem became curious as to whether there is an association between how animated the lead singer is and the amount of applause from the audience. He decided to watch each singer and rate the singer on a scale of 1 to 5 , where 1 is the least animated and 5 is the most animated. He did this for all 5 nights of auditions and found that the more animated singers did receive louder applause. The study Liem conducted would be best described as
Chuck's Trucking Company has decided to initiate an Employee of the Month program. To determine the recipient, they put the following sign on the back of each truck.
The driver who receives the highest number of positive comments will win the recognition. Explain one statistical bias in this data collection method.
Explain one statistical bias in this data collection method.
A public opinion poll was conducted on behalf of Mayor Ortega's reelection campaign shortly before the election. 264 out of 550 likely voters said they would vote for Mayor Ortega; the rest said they would vote for his opponent.
Which statement is least appropriate to make, according to the results of the poll?
Robin flips a coin 100 times. It lands heads up 43 times, and she wonders if the coin is unfair. She runs a computer simulation of 750 samples of 100 fair coin flips. The output of the proportion of heads is shown below.
Do the results of the simulation provide strong evidence that Robin's coin is unfair? Explain your answer.
Do the results of the simulation provide strong evidence that Robin's coin is unfair? Explain your answer.
Two classes of students were entered into an experiment to see whether using an interactive whiteboard leads to better grades. It was observed that the mean grade of students in the class with the interactive whiteboard was 0.6 points higher than the class without it. To determine if the observed difference is statistically significant, the classes were rerandomized 5000 times to study these random differences in the mean grades. The output of the simulation is summarized in the histogram below.
Determine an interval containing the middle 95% of the simulation results. Round your answer to the nearest hundredth.
Does the interval indicate that the difference between the classes' grades is significant? Explain.
Determine an interval containing the middle 95% of the simulation results.
Does the interval indicate that the difference between the classes' grades is significant? Explain.
The operator of the local mall wants to find out how many of the mall's employees make purchases in the food court when they are working. She hopes to use these data to increase the rent and attract new food vendors. In total, there are 1023 employees who work at the mall. The best method to obtain a random sample of the employees would be to survey
Using a microscope, a researcher observed and recorded the number of bacteria spores on a large sample of uniformly sized pieces of meat kept at room temperature. A summary of the data she recorded is shown in the table below.
Hours | Average Number of Spores |
---|---|
0 | 4 |
0.5 | 10 |
1 | 15 |
2 | 60 |
3 | 260 |
4 | 1130 |
6 | 16,380 |
Using these data, write an exponential regression equation, rounding all values to the nearest thousandth.
The researcher knows that people are likely to suffer from food-borne illness if the number of spores exceeds 100. Using the exponential regression equation, determine the maximum amount of time, to the nearest quarter hour, that the meat can be kept at room temperature safely.
Write an exponential regression equation using the given data.
Determine the maximum safe time for keeping meat at room temperature.
A group of high school students wanted to collect information on how many times per week students exercised. If they want the least biased results they should survey every fifth student at the school who is
Suppose two sets of test scores have the same mean, but different standard deviations, and , with . Which statement best describes the variability of these data sets?