In how many ways can 3 seats be occupied if 5 people are willing to sit?
60
20
5
120
Correct answer is A
5 people can take 3 places in;
5P3 ways, = 5!(5−3)! = 5!2!
= 5×4×3×2!2!
= 5 x 4 x 3
= 60 ways
In how many ways can a student select 2 subjects from 5 subjects?
5!3!
5!2!2!
5!2!3!
5!2!
Correct answer is C
A student can select 2 subjects from 5 subjects in;
5C3 ways, i.e. = 5!2!(5−2)!
= 5!2!3!
7
6
3
10
Correct answer is A
Range = Highest score - Lowest score
= 10 - 3
= 7
If the variance of 3+x, 6, 4, x and 7-x is 4 and the mean is 5, find the standard deviation
√3
2
3
√2
Correct answer is B
Let δ2 and δ denote the variance and standard deviation of the distribution respectively.
But δ2 = 4 (given)
Hence δ = √4 = 2
25
30
35
20
Correct answer is A
N = ∑f = 15
Hence the median age is the N+12th age, i.e.
15+12th = 8th
From the table, the age that falls on the 8th position when arranged in ascending order is 25years