A researcher records the following times (in seconds)that it took a group of mice to complete a maze: 23 4.1 (M SD).The top 10% of mice finishing with the fastest times will be placed in a "maze bright" group.What is the cutoff time to be placed in this group?
A)17.75 seconds
B)28.25 seconds
C)faster than 16 seconds
D)There is not enough information to answer this question.

Question

A researcher records the following times (in seconds)that it took a group of mice to complete a maze: 23  4.1 (M  SD).The top 10% of mice finishing with the fastest times will be placed in a "maze bright" group.What is the cutoff time to be placed in this group?
A)17.75 seconds 
B)28.25 seconds 
C)faster than 16 seconds 
D)There is not enough information to answer this question.

Quizplus · Accepted Answer

To find the cutoff time for the top 10% of mice, we need to calculate the 90th percentile of the data. We can do this by first sorting the data from smallest to largest: 
4.1, 11, 23 
The 90th percentile is the value that is greater than 90% of the data. In this case, since we have 3 data points, 90% of the data is 0.9*3 = 2.7, which rounds up to 3 when we count it. So, the 90th percentile is the 3rd value in the sorted data set, which is 23. Therefore, any mice that completed the maze in 23 seconds or less will be in the top 10% and be placed in the "maze bright" group. Choice B is the only option that matches this cutoff time.

A Researcher Records the Following Times (In Seconds)that It Took