## Description

**STA 1305: INTRODUCTION TO BUSINESS STATISTICS/BUSINESS STATISTICS I **

OPEN BOOK QUIZ

Attempt ALL Questions

- According to the Central Bank of Kenya, between 1989 and 2013 the median family net worth (in 2013 shillings) changed from Sh. 85,060 to Sh. 81,400 whereas the mean family net worth changed from Sh. 342,300 to Sh. 528,420. What do these statistics suggest about the change in the distribution of family net worth from 1989 to 2013? Why?

[3 marks]

- In a certain survey, in response to the question “Do you believe in life after death?” 1127 people answered “yes” and 199 answered “no.”
- Estimate the probability that a randomly selected person believes in life after death. [2 marks]
- Estimate the probability that a person does not believe in life after death.

[2 marks]

iii. Of those who believe in life after death, about 84% believe hell exists. Estimate the probability that a randomly chosen person believes in both life after death and the existence of hell. [3 marks]

- In a certain study subjects were asked whether astrology—the study of star signs—has some scientific truth. Of 1245 sampled subjects, 651 responded definitely or probably true, and 594 responded definitely or probably not true. The proportion responding definitely or probably true was 651/1245 = 0.523.

i.) Describe the population of interest. [2 marks]

ii.) For what population parameter might we want to make an inference? [1 mark]

iii.) What sample statistic could be used in making this inference? [1 mark]

iv.) Does the value of the statistic in (iii) necessarily equal the parameter in (ii)? Explain. [3 marks]

- With quota sampling a researcher stands at a street corner and conducts interviews until obtaining a quota representing the relative sizes of various groups in the population. For instance, the quota might be 50 factory workers, 100 housewives, 60 elderly people, and 30 blacks. Is this a probability or nonprobability sampling method? Explain, and discuss potential advantages or disadvantages of this method. [5 marks]
- The table below gives yearly automobile operating expenses in a particular region in Kenya

Item |
2016 |
2017 |
|||||||

Price (Sh) | Quantity (Kg) | Price (Sh) | Quantity (Kg) | ||||||

Petrol | 83 | 1200 | 109 | 1350 | |||||

Oil | 58 | 250 | 61 | 300 | |||||

Tire | 200 | 40 | 250 | 60 | |||||

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