q1solutions - Statistics 20: Quiz 1 Solutions Speed (mph)...

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Statistics 20: Quiz 1 Solutions Speed (mph) Percentage of Total Cars 0-10 20 10-20 10 20-40 40 40-80 20 80-95 10 The above table depicts data collected in a (hypothetical) survey studying the distribution of traffic speed on the Bay Bridge. Each group includes the left end-point but not the right. (So, for instance, the first group includes cars driving 0 mph (not moving) but does not include cars driving exactly 10 mph.) Use this information to answer Questions 1-3. You may draw a histogram of these data if it helps you, but it is not necessary for answering the questions. 1. Would you estimate that there are more cars driving less than 1 mph than cars driving be- tween 21 and 22 mph? Note: the interval is [21,22). For any class interval, we estimate the proportion of data falling in one of its sub-intervals by the equation Percent in sub-interval = Percent in class * Length of Sub-Interval Length of class interval . Based upon this, the percent of data in [0 , 1] is approximately 20% ± 1 - 0 10 - 0 ² = 2%. Likewise, the percent of data in [21 , 22) is approximately 40% ± 22 - 21 40 - 20 ² = 2%. Therefore, we estimate that both class intervals have the same percentage of all cars on the Bay Bridge within them. As a result, we must answer
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This note was uploaded on 04/02/2008 for the course STAT 21 taught by Professor Anderes during the Spring '08 term at University of California, Berkeley.

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q1solutions - Statistics 20: Quiz 1 Solutions Speed (mph)...

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