Question 1

As a researcher conducting work at a local visitor attraction you count the number of visitors every day for a week, recording gender and the number of adult and child tickets sold. How might this data be classified?

Accepted Answer

The data is primary because it is being collected firsthand by the researcher for a specific purpose. It is discrete because the number of visitors, gender, and tickets sold are countable items that cannot be broken down into smaller parts.

Question 2

What term is used when numbers are rounded in one direction only (e.g. ages are usually only rounded down)?

Accepted Answer

Biased rounding refers to the process of rounding numbers in a single, consistent direction, which introduces a systematic bias to the rounded figures. This term accurately describes the scenario where ages are only rounded down.

Question 3

An insurance company reports the average number of transactions each day as 1,850 (n10). What is the correct range of possible true values?

Accepted Answer

The range [1,845, 1,855] is a reasonable estimate for the average number of transactions, allowing for a small margin of error around the reported average of 1,850.

Question 4

A ball-bearing factory makes 4,000,000 ±5% ball bearings each day. Which option below represents the minimum and maximum number of ball bearings actually produced each day?

Accepted Answer

The minimum number is 4,000,000 - 5% of 4,000,000 = 3,800,000, and the maximum number is 4,000,000 + 5% of 4,000,000 = 4,200,000.

Question 5

Which answer below IS an example of planned or predictable error?

Accepted Answer

Rounding of discrete data is a planned or predictable error because it is a deliberate simplification of data for ease of use or analysis, knowing that it introduces a small, systematic error.

Question 6

Why is it usually considered preferable to use numbers subject to compensating errors rather than numbers subject to systematic errors?

Accepted Answer

Compensating errors tend to cancel each other out when combined, leading to a result that is closer to the true value, whereas systematic errors consistently skew results in one direction.

Question 7

You have been asked to estimate the number of books in school libraries in Izmir, Turkey. You know there exactly 85 schools and that on average each library has 12,500 (n100) books. What is the correct range of values?

Accepted Answer

The total number of books is calculated by multiplying the number of schools (85) by the average number of books per library (12,500). This gives 1,062,500 books. The range given in option D, [1,058,250, 1,066,750], is the only one that includes this calculated total, making it the correct range of values.

Question 8

The average cost of a week-long holiday for 2 adults and 2 children is reported as being AED 10,200 (Emirati Dirham). You know the actual value was calculated as AED 10,197.89 but that it has been rounded. What is this process called?

Accepted Answer

The process is called "fair rounding" because the value was rounded to the nearest whole number in a neutral manner, without systematically overestimating or underestimating the value.

Question 9

A colleague tells you that the average price of Zinc has increased by 33% in 3 years. In the same period, the price of Copper has increased by 25% Which of the following statements IS true?

Accepted Answer

The statement that the percentage increase in the price of Zinc (33%) is greater than the percentage increase in the price of Copper (25%) is directly given in the information provided. The other options cannot be determined as true based solely on the information given.

Question 10

A farmer records wheat production as being 2.5 tons per hectare. Which is NOT a potential source of error in this calculation?

Accepted Answer

The answer of A farmer records wheat production as being...

Quiz 3: Data and Their Accuracy