Statistics - Online Test
Q1. Which one of the following average is most affected of extreme observations ?
Answer : Option D
Explaination / Solution:
As A/M is calculated as the sum of all the observations divided by number of observations, so it is affected by if there is any change in the outliers
Q2. The H.M. of 4,8,16 is
Answer : Option B
Explaination / Solution:
H.M=31a+1b+1c=314+18+116=48/7=6.85
Q3. The Mode of the following items is 0,1,6,7,2,3,7,6,6,2,6,0,5,6,0.
Answer : Option B
Explaination / Solution:
6 is the most frequent value here.
Q4. The statistical method which helps us to estimate or predict the unknown value of one variable from the known value of the related variable is called
Answer : Option B
Explaination / Solution:
It follows from the definition of regression
Q5. The coefficient of correlation r satisfies
Answer : Option D
Explaination / Solution:
r can't be numerically more than 1
Q6. S.D. of a data is 6. When each observation is increased by 1, then the S.D. of new data is
Answer : Option D
Explaination / Solution:
so it depends only on number of observations not on individual observations.
Q7. The most stable measure of central tendency is
Answer : Option C
Explaination / Solution:
because takes into account every value in the given set of data to provide the average
Q8. The mean weight of a group of 10 items is 28 and that of another group of n items is 35.The mean of combined group of 10 + n items is found to be 30. The value of n is
Answer : Option A
Explaination / Solution:
sum of weights of 10 items =280
sum of weights of n items = 35n
so, sum of weights of ( 10 + n) items = 280 + 35n
so ,mean = (280 + 35 n) / ( 10 + n)
30(10 + n ) = 280 + 35n
solving we get, n = 4
Q9. The measure of variation which is least affected by extreme items is
Answer : Option C
Explaination / Solution:
as it only depends on upper and lower quartile not on extreme values
Q10. A group of 10 items has mean 6. If the mean of 4 of these items is 7.5, then the mean of the remaining items is
Answer : Option D
Explaination / Solution:
sum of 10 items = 60
sum of 4 items = 30
sum of remaining items = 30
their mean = 30/6=5
