Vidaara.orgClass 11 · Mathematics
CodeVID-M11-WS
Correlation — Practice Worksheet
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Choose the correct option (A, B, C or D) for each question.
- The answer key is at the end — try the paper first!
Section A — Multiple Choice (1 mark each)
15 × 1 = 15 marks
1.
Correlation measures the ____ between two variables.
- A.Sum
- B.Relationship
- C.Average
- D.Frequency
2.
When both variables move in the same direction, correlation is:
- A.Positive
- B.Negative
- C.Zero
- D.Perfect negative
3.
Price and demand usually show ____ correlation.
- A.Positive
- B.Negative
- C.Zero
- D.Perfect positive
4.
A graph plotting pairs of values as dots is a:
- A.Histogram
- B.Scatter diagram
- C.Pie chart
- D.Ogive
5.
On a scatter diagram, dots falling from left to right show:
- A.Positive correlation
- B.Negative correlation
- C.No correlation
- D.Perfect positive
6.
Karl Pearson's coefficient r always lies between:
- A.0 and 1
- B.−1 and +1
- C.−10 and +10
- D.1 and 100
7.
r = +1 means:
- A.Perfect positive correlation
- B.Perfect negative correlation
- C.No correlation
- D.Weak correlation
8.
r = 0 means:
- A.Perfect correlation
- B.No correlation
- C.Strong correlation
- D.Negative correlation
9.
Pearson's formula uses deviations from the:
- A.Mode
- B.Mean
- C.Median
- D.Range
10.
If Σ(dx·dy)=300, Σdx²=100, Σdy²=900, then r equals:
- A.1
- B.0.5
- C.0
- D.−1
11.
Spearman's rank correlation is used for:
- A.Ranked or qualitative data
- B.Only exact measurements
- C.Pie charts
- D.Time series only
12.
In Spearman's formula, D stands for the:
- A.Difference between the two ranks
- B.Mean
- C.Total
- D.Frequency
13.
Spearman's R = 1 − [6ΣD² ÷ N(N²−1)]. For ΣD²=4, N=5, R is:
- A.0.8
- B.0.2
- C.−0.8
- D.1
14.
A correlation coefficient close to 0 indicates:
- A.Strong correlation
- B.Weak or no correlation
- C.Perfect correlation
- D.Causation
15.
The statement 'correlation is not causation' warns that:
- A.A third factor may cause both variables
- B.r is always wrong
- C.Ranks cannot be used
- D.Scatter diagrams are useless
Section B — Challenge / Olympiad (2 marks each)
10 × 2 = 20 marks
16.
As a household's income rises, its consumption also rises. The correlation between income and consumption is:
- A.Positive
- B.Negative
- C.Zero
- D.Perfect negative
17.
A scatter diagram whose dots lie almost exactly on an upward straight line indicates:
- A.Strong (near-perfect) positive correlation
- B.Negative correlation
- C.No correlation
- D.A pie chart
18.
For data where Σ(dx·dy) is negative while Σdx² and Σdy² are positive, the value of r is:
- A.Negative
- B.Positive
- C.Exactly zero
- D.Greater than 1
19.
Two examiners rank 5 students and get ΣD² = 0. The rank correlation R is:
- A.+1
- B.0
- C.−1
- D.0.5
20.
Spearman's method is chosen over Pearson's when the data are about qualities like beauty or honesty because such qualities can only be:
- A.Ranked, not exactly measured
- B.Added together
- C.Drawn as pies
- D.Ignored
21.
The number of umbrellas sold and the amount of rainfall show high positive correlation. The most likely reason is:
- A.Rain genuinely drives umbrella sales (a real relationship)
- B.Umbrellas cause rain
- C.Pure coincidence with no link
- D.A third hidden factor only
22.
An r of −0.92 between two variables means they are:
- A.Strongly inversely related
- B.Weakly related
- C.Unrelated
- D.Perfectly positively related
23.
Karl Pearson's r can be distorted by extreme values because it is based on:
- A.Deviations from the mean
- B.Ranks
- C.The mode
- D.Cumulative frequency
24.
If two judges rank items in exactly the opposite order, the rank correlation R will be:
- A.−1
- B.+1
- C.0
- D.0.5
25.
A scatter of dots with no upward or downward pattern indicates that r is close to:
- A.0
- B.+1
- C.−1
- D.10
Answer Key
Section A — Multiple Choice (1 mark each)
- (B) Relationship
- (A) Positive
- (B) Negative
- (B) Scatter diagram
- (B) Negative correlation
- (B) −1 and +1
- (A) Perfect positive correlation
- (B) No correlation
- (B) Mean
- (A) 1
- (A) Ranked or qualitative data
- (A) Difference between the two ranks
- (A) 0.8
- (B) Weak or no correlation
- (A) A third factor may cause both variables
Section B — Challenge / Olympiad (2 marks each)
- (A) Positive
- (A) Strong (near-perfect) positive correlation
- (A) Negative
- (A) +1
- (A) Ranked, not exactly measured
- (A) Rain genuinely drives umbrella sales (a real relationship)
- (A) Strongly inversely related
- (A) Deviations from the mean
- (A) −1
- (A) 0
Generated by Vidaara.org · Assignment VID-M11-WS · vidaara.org