Question

The mean number of days it rained in the month of August for a 5-year period at a local airport was 7 with a standard deviation of 2. The average amount of rainfall during that same month and period at that airport was 9 inches with a standard deviation of 3 inches.

Which variable has the lower relative variation?

amount of rainfall

number of days it rained

amount of rainfall but not the number of days it rained

neither

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The following stem-and-leaf plot represents a sample of exam scores.
     
Exam Scores
      4 | 5 6 8
      5 | 3 4 5 6 9
      6 | 2 3 5 6 6 9 9
      7 | 0 1 1 3 3 4 5 5 5 7 8
      8 | 1 2 3 6 9
      9 | 3 5 7 8

The interquartile range for the examination scores is

QQQQ

The following stem-and-leaf plot represents a sample of exam scores.
     
Exam Scores
      4 | 5 6 8
      5 | 3 4 5 6 9
      6 | 2 3 5 6 6 9 9
      7 | 0 1 1 3 3 4 5 5 5 7 8
      8 | 1 2 3 6 9
      9 | 3 5 7 8

The mean absolute deviation for the examination scores is

QQQ

The following are given for a set of values:
I.    The values ranged from 40 to 95.
II.   The median value was 79.
III. 25 percent of the values are less than or equal to a value of 60.
IV. 75 percent of the values are less than or equal to 87.

From the above information, the third quartile for the data set is

Answer 1

1. Relative deviation = standard deviation / mean

Relative deviation of amount of rainfall = 3/9 = 0.33

Relative deviation of number of days it rained = 2/7 = 0.285

Thus b) number of days it rained has lower relative deviation.

2. From stem and leaf plot, we see number of exam scores are 35 i.e. n= 35

Lower quartile = (n+1)/4 th number = 9th number = 62

Upper quartle = 3(n+1)/4 th number = 27th number = 81

Inter quartile range = upper quartile - lower quartile = 81-62 = 19