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Twenty students each solve a puzzle. Their times in seconds, from a made-up class activity, are 12…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Twenty students each solve a puzzle. Their times in seconds, from a made-up class activity, are , , , and . Draw up bins of width 10 seconds, starting at 10 seconds, with an edge value going into the bin above. How many bins are needed? How many students are in the bin 30 to 40 seconds, and how many in the bin 50 to 60 seconds?
Need a reminder? The key ideaShow
A histogram counts numerical values into bins of equal width, with touching bars. An edge value goes into the bin above. With unequal bins the height is the frequency density:
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The bins. The times run from 12 s to 58 s, so the bins 10 to 20, 20 to 30, 30 to 40, 40 to 50 and 50 to 60 cover them. That is 5 bins.
Step 2. Count 30 to 40. The times 30, 31, 33, 34, 36 and 38 seconds are in this bin. The time 40 s is on the next edge, so it goes into 40 to 50. The count is 6.
Step 3. Count 50 to 60. The times 52 s and 58 s. The count is 2.
Answer: 5 bins, 6 students and 2 students.
Check. All five counts are 3, 6, 6, 3 and 2. They add up to 20, the number of students.
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