1.
For the data 2, 5, 7, 7, 10, 11, 15, find the median. [2]
JD SCIENCE
Statistics
Answer all questions. Show working. Answers are in a separate file on the Worksheets page — do not look at them until you have finished.
2.
Find the mode of that data set. [1]
3.
Find the range of that data set. [1]
4.
Find the mean of that data set. Give your answer to 1 d.p. if needed. [2]
5.
The mean of four numbers is 10. Three of the numbers are 7, 9 and 12. Find the fourth number. [3]
6.
Which average is most affected by an outlier: mean, median or mode? Explain. [2]
7.
A frequency table: 1,2,3,4,5 scored by 4, 6, 7, 3, 0 students.
(a) How many students were surveyed? [2]
(b) Estimate the mean score. [3]
8.
From the same table, find the modal score and the median score. [3]
9.
Explain the difference between a bar chart and a histogram. [3]
10.
A histogram has a class 10 ≤ t < 20 of width 10 and frequency 16. Find the frequency density. [2]
11.
A scatter graph shows a strong negative correlation. Describe what this means in context if the variables are age of a car and value. [2]
12.
Why does correlation not imply causation? Give an exam-style example. [2]
13.
Stem-and-leaf: 1 | 2 5 ; 2 | 0 3 7 8 ; 3 | 1 4. Find the median and the range. [3]
14.
Quartiles for 11 ordered values: find the positions of Q1, Q2 and Q3. [2]
15.
A data set has Q1 = 4, Q3 = 12. Find the interquartile range and explain what it measures. [3]
16.
An outlier is often defined as a value more than 1.5 × IQR above Q3 or below Q1. If Q1 = 10, Q3 = 22, which of 42 and 40 would be outliers? [3]
17.
Two groups: A has mean 20 from 10 people, B has mean 30 from 20 people. Find the combined mean. [3]
18.
Describe how to draw a box plot from a five-number summary. [3]
19.
Compare two box plots: team A has a higher median but a larger IQR than team B. Write a comparison in context of test scores. [3]
20.
Grouped data: 0–10 fd=2, 10–20 fd=5, 20–40 fd=3. The second class is 10 wide. Find its frequency. [2]
21.
What is frequency density and why is it used in a histogram with unequal class widths? [2]
22.
A pie chart represents 180 students. The 'walk' sector is 80°. How many students walk? [2]
23.
In a sample of 40, 7 people own a cat. Estimate how many own a cat in a town of 12 000, assuming the sample is representative. [2]
24.
Give one reason a sample might not be representative, and one way to improve it. [2]
25.
Explain the difference between discrete and continuous data. Give an example of each. [2]
26.
Moving average: sales 4, 8, 6, 10. Calculate the 3-point moving averages. [3]
27.
What is the purpose of a moving average on a time series? [2]
28.
Devon records 5, 7, a, 9. The mean is 8. Find a. [2]
29.
A cumulative frequency graph is drawn for 80 times.
(a) How do you read the median from the graph? [1]
(b) How do you estimate the IQR? [2]
30.
A student says the mean of 1, 2, 3, 100 is a good typical value. Critique this. [2]
31.
On Edexcel statistics questions, you are often asked to compare distributions. Write the two things you must compare. [2]
32.
Index numbers: price in year 0 is £2.50 (index 100). Year 1 price is £3.00. Find the index number for year 1. [2]