STAT213 Tutorial sheet #2

 

In a blue box survey, 78% of households recycle paper, 60% recycle plastic and 52% recycle both paper and plastic.

1)      What percentage of households recycle either paper or plastic? (86%)

2)      Based on the probabilities, which households are more likely to recycle plastic: those that recycle paper or those that don’t recycle paper? From this, can we conclude that recycling one thing depends on recycling the other? (those that recycle paper)

3)      What is the probability a household does not recycle paper if it doesn’t recycle plastic? (35%)

4)      Explain why a household recycling both paper and plastic are not mutually exclusive events. (see key)

 

A credit card company conducted a survey with 10,000 people to determine if there is a link between annual household income and credit card balances. These were the results:

Balance|Income

<$35K

$35K to under $50K

$50K to under $75K

$75K to under $100K

$100K+

Total

< $500

107

508

191

0

0

806

$500 to under $1000

169

1377

826

254

64

2690

$1000 to under $5000

0

890

1419

911

254

3474

$5000+

0

254

805

1229

742

3030

Total

276

3029

3241

2394

1060

10000

5)      What percentage has a credit card balance under $1000? (34.96%)

6)      What percentage of those who earn between $35,000 and $50,000 has a credit card balance under $1000? (62.23%)

7)      What percentage of those who earn less than $75,000 has a credit card balance under $1,000? (48.55%)

8)      What percentage of those who have a credit card balance of at least $1000 has an annual household income of at least $50,000 (82.41%)

9)      Which income group is the most likely to have a credit card balance of at least $1000? What is the trend  in the percentage of each income group that has a credit card balance of at least $1000? ($100K+ at 93.96%; the percentage increases with each income group)

 

10)  You are given the following table:

Brand

% market share

% used by

under 25 age group

Brand A

25

70

Brand B

15

55

Brand C

60

40

What is the overall market share of the under 25 age group? Which brand has the largest market share of this group and what percentage of this group does it have? (overall = 49.75%; brand C at 48.24%)

 

A survey of work commute habits was conducted. Respondents were divided into inner city and suburbs. These are some of the findings:

·         76.2% live in the suburbs

·         Of those living in the suburbs, 25.2% take transit at least once a week to work

·         Of those living in the inner city, 12.8% take transit at least once a week to work

11)  What is the overall percentage of those who take transit at least once a week to work? (22.25%)

12)  Of those who take transit at least once a week to work, what percentage live in the suburbs? (86.31%)

13)  Of those who take transit less than once a week to work, what percentage live in the inner city? (26.69%)