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Home > MC1 > Chapter 8 > Lesson 8.2.3 > Problem 8-57


To find her usual bedtime, Zoe kept a record of what time she went to bed. These are the times she recorded: 9:30 p.m., 10:30 p.m., 10:00 p.m., 9:00 p.m., 11:00 p.m., 9:00 p.m., 9:30 p.m., 10:00 p.m., 11:00 p.m., and 9:00 p.m.

  1. What is the mode of Zoe's bedtimes?

  1. What is the median?

  2. When you calculate the mean, what values will you use for 9:30 p.m. and 10:30 p.m.?

  3. What is the mean?

  4. If Zoe wants to convince her parents that she usually goes to bed early and should be allowed to stay up late this Friday, which of these measures of central tendency would she probably choose to use? Explain.

Try putting the bedtimes in order from earliest to latest first. This might help you find the measures of central tendency more easily.

Remember that the mode is the most frequently repeated piece of data. What time did Zoe go to bed the most?

In the list of data you made in part (a), the median will be one in the exact middle, between the earliest and latest times.

Because there is an even number of bedtimes listed, take the average time of the two middle times.

If there are 60 minutes in an hour, what portion of an hour is 30 minutes?

You should use 9.5 and 10.5 to find the mean.

The mean is 9.85, which is about 9:51 p.m.

Look at the modes of central tendancy you found in parts (a), (b), and (d).
The earliest time would probably be the best time for Zoe to refer to. Remember to explain your answer!