Grade 12 Consumer Oct. 27-28

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Which age group watches the most TV in a week?
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2. Introduction to Statistics
Data ­ numbers collected in a particular context that are studied for a purpose
Statistics ­ branch of mathematics that tries to make meaning of the
collected data.
measure of central tendency
an average of the set of data and tends to be located near the centre of the data
• Mean
• Median
• Mode
*Range ­
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3. Memory Test A
light scratch
shower work
chicken program
soccer baby
water computer
kitchen magazine
gymnasium family
garbage bowling
bell ceiling
sleep countertop
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5. Memory Test B
sound watch
curtain bench
basketball thunderstorm
street rooster
dress machine
garage library
cafeteria brother
star house
shell alcohol
grocery winter
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7. Percentiles
Percent score
­ how well you would have done on the test if it were marked out of 100
Example:
Marjoy writes a test and scores 48 out of possible 60
marks. Express this mark as a rate of percent.
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8. Percentile Rank
Comparing a Raw Score to All Other Scores
Suppose 100 students have written the same test as Marjoy.
Suppose only 10 of these students score less than 48 out of 60.
How does Marjoy's mark compare with the marks of the other
students who have written the same test?
Assume that no other student has scored exactly 48 out of 60.
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9. Suppose, however, that of the 100 students who have written the same test
as Marjoy, 90 of them score lower than 48 out of 60.
How does Marjoy’s mark now compare with the marks of the other
students?
Assume no other student scores 48 out of 60.
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10. Percentile Rank
indicates the percent of all scores that fall below a particular score.
• The higher the percentile rank, the better the score
compared to the other scores.
• The lower the percentile rank, the poorer the score
compared to the other scores.
B = number of scores Below a given score
E = number of scores Equal to the given score, including the given score.
*if there are no other scores equal to the given score, then E = 0.
n = total number of scores
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11. The following is a set of 32 marks achieved by students on an examination worth 100 marks.
Determine the percentile ranking for a raw score of 72.
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12. Mac writes a college entrance examination and scores
1440 out of a possible 1800. Of the 875 students writing
the college entrance examination, 25 other students have
the same score as Mac and 680 students have lower
scores than him.
a) Find Mac's percentile rank.
b)In order to be considered for a particular college
program, Mac needs a percentile rank of 75 or better.
Is Mac's score high enough for him to be considered
for the program?
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13. Special Percentile Notation
You can also use the letter P and a subscript to denote a particular percentile
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14. A survey is conducted of a community of 2000 families.
The survey yields the following percentiles on family income.
P25 = $23,500 P50 = $32,000
P75 = $48,000 P90 = $100,000
• Approximately what percentage of families in the community earn more
than $100,000 a year?
• Approximately what percentage of families in the community earn less
than $48,000 a year?
• Approximately how many families in the community earn less than
$23,500 a year?
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15. P25 = $23,500 P50 = $32,000
P75 = $48,000 P90 = $100,000
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16. Complete: Assignment 1
iz tom orrow
for a qu
Pre pare
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