B Apply

18. Think About a Plan The numbers of paper clips per box in a truckload of boxes are normally distributed, with a mean of 100 and a standard deviation of 5. Find the probability that a box will not contain between 95 and 105 clips.
    • How should you label the vertical lines on the graph of the normal distribution?
    • Which parts of the graph are not between 95 and 105 clips?
19. 1. From the table below, select the set of values that appears to be distributed normally.
    2. Using the set you chose in part (a), make a histogram of the values.
    3. Sketch a normal curve over your graph.

    Set 1	Set 2	Set 3
    1	5	5
    10	7	6
    5	7	9
    19	7	1
    2	4	1
    7	11	5
    1	7	11
    7	7	1
    2	7	10
    10	9	4
    6	7	2
    9	7	8

20. Writing In a class of 25, one student receives a score of 100 on a test. The grades are distributed normally, with a mean of 78 and a standard deviation of 5. Do you think the student's score is an outlier? Explain.

21. Sports To qualify as a contestant in a race, a runner has to be in the fastest 16% of all applicants. The running times are normally distributed, with a mean of 63 min and a standard deviation of 4 min. To the nearest minute, what is the qualifying time for the race?
22. Agriculture To win a prize, the diameter of a tomato must be greater than 4 in. The diameters of a crop of tomatoes grown in a special soil are normally distributed, with a mean of 3.2 in. and a standard deviation of 0.4 in. What is the probability that a tomato grown in the special soil will be a winner?

A normal distribution has a mean of 100 and a standard deviation of 10. Find the probability that a value selected at random is in the given interval.

23. from 80 to 100
24. from 70 to 130
25. from 90 to 120
26. at least 100
27. at most 110
28. at least 80
29. Weather The table below shows the number of tornadoes that were recorded in the U.S. in 2008.

    Month	Tornadoes
    1	84
    2	147
    3	129
    4	189
    5	461
    6	294
    7	93
    8	101
    9	111
    10	21
    11	20
    12	40

    1. Draw a histogram to represent the data.
    2. Does the histogram approximate a normal curve? Explain.
30. Error Analysis In a set of data, the value 332 is 3 standard deviations from the mean and the value 248 is 1 standard deviation from the mean. A classmate claims that there is only one possible mean and standard deviation for this data set. Do you agree? Explain.

31. Reasoning Jake and Elena took the same standardized test, but with different groups of students. They both received a score of 87. In Jake's group, the mean was 80 and the standard deviation was 6. In Elena's group, the mean was 76 and the standard deviation was 4. Did either student score in the top 10% of his or her group? Explain.

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