The mean and variance of n observations x1, x2, ....x xn are 5 and 0 respectively. If xi2 = 400, then the value of n is equal to.
80
25
20
16
1/5
-1/5
-2/5
2/5
If in a frequency distribution, the mean and median are 21 and 22 respectively, then its mode is approximately.
24
25.5
20.5
22.0
The values of mean, median and mode coincide, then the distribution is:
Positive skewness
Symmetric distribution
Negative skewness
All of the above
and n = 10, then the coefficient of correlation is:
0.1
0.3
0.2
The mean deviation from the mean of the set of observations -1, 0, 4 is
3
1
-2
2
Consider the following statements i. Mode can be computed from histogram ii. Median is not independent of change of scale iii. Variance is independent of change of origin and scale Which of these is/ are correct?
Only (1)
Only (ii)
Only (i) and (ii)
Only (i), (ii) and (iii)
The standard deviation of n observations x1, x2, ---xn is 2. If xi2 = 100, then n is
10 or 20
5 or 10
5 or 20
5 or 15
If var (x) = 8.25, var (y) = 33. 96 and cov (x,y) = 10.2then the correlation coefficient is:
0.89
-0.98
0.61
-0.16
In a class of 100 students there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class is 72, then what is the average marks of the girls?
73
65
68
74
