One variable that is measured by online homework systems is the amount of time a
ID: 3318939 • Letter: O
Question
One variable that is measured by online homework systems is the amount of time a student spends on homework for each section of the text. The following is a summary of the number of minutes a student spends for each section of the text for the fall 2010 semester in a college algebra class at Joliet Junior College.
Q1 = 42 Q2 = 51.5 Q3 = 72
a) provide an interpretation of these results.
b) determind and interpret the interquartile range
c) suppose a student spent 2 hours doing homework for a section. Is this an outlier?
d) do you believe that the distribution of time spent doing homework is skewed or symmetric? Why?
Explanation / Answer
(a) The middle 50% of students spend between 42 to 72 minutes on their homework. 25% of students spend more than 72 minutes on their homework where as 25% students spend less than 42 minutes on their homework.
(b) IQR = Q3 - Q1 = 72 – 42 = 30 minutes
The middle of 50% of all students has a range of 30 minutes of time spent on homework.
(c) Observation value lower than Q1-1.5*IQR will be treated as outliers.
Q1=42
IQR = Q3 - Q1 = 72 – 42 = 30
Q1-1.5*IQR = 42 - 1.5*30 = -3
As 2>-3, so if a student spent 2 hours doing homework for a section, it will not be treated as an outlier.
(d) Right-skewed because the difference between Q2 and Q1 is less than the difference between Q3 and Q2.
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