Welcome to your Grade 9 Mathematics chapter 8
After carefully reading the following 30 questions, choose the correct answer.
1.
The arithmetic mean of n observations x1,x2,…,xn is defined as:
2.
Calculate the mean of the data set: 5,4,6,4,3,6,7.
3.
The sum of the deviations of observations from their mean is always:
4.
If a constant k is added to each value in a data set, the new mean will be:
5.
Which measure is used to quantify the scatter or spread of data?
6.
If each value in a data set is multiplied by a constant c, the new variance is:
7.
The square root of the variance is called the:
8.
If the mean of 2,3,x,5,6,12 is 5, find x.
9.
When a constant k is added to each observation, the standard deviation:
10.
The mean of marks scored by 40 students was 72.5. If one score was 48 but should have been 84, the correct mean is:
11.
In a frequency distribution, the mean is calculated using the formula xˉ=∑fi∑fixi. What does fi represent?
12.
Ten people have pencils: 6,5,6,5,3,6,6,10,10,3. What is the mean number of pencils?
13.
If the mean of y+2,y+4,y+6,y+10 is 13, what is the value of y?
14.
The mean monthly salary of 12 employees is Birr 1450. If one person joining gets Birr 1645, the new mean is:
15.
If the mean of a,b,c,d is k, what is the mean of a+b,2b,c+b,b+d?
16.
Variance (σ2) is defined as the mean of the:
17.
For the data 2,3,4,3, the mean is 3. What is the variance?
18.
If each value of data is multiplied by c, the new standard deviation is:
19.
In the frequency distribution of test scores for 10 students, if the sum of fixi is 330, the mean is:
20.
Property 1 of variance states that adding a constant k to all values:
21.
The value that appears most frequently in a data set is the:
22.
The middle value of a data set when arranged in order is the:
23.
If a data set has values 82,23,59,94,70,26,32,83,87,94,32, what is the mode?
24.
For a set of n observations, the mean is denoted by the symbol:
25.
In the property of mean, if x1,…,xn have mean xˉ, then (x1−xˉ)+(x2−xˉ)+⋯+(xn−xˉ) is:
26.
If the variance of a data set is 0.25, what is the standard deviation?
27.
Comparing sets of data is often done by measuring the:
28.
If the mean of a data set is 10 and you add 5 to every value, the new mean is:
29.
The notation ∑i=1nfi represents:
30.
Standard deviation is denoted by the Greek letter:
