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, = \(\frac{5!}{(5 - 3)!}\) = \(\frac{5!}{2!}\)
= \(\frac{5 \times 4 \times 3 \times 2!}{2!}\)
= 5 x 4 x 3
= 60 ways
In how many ways can a student select 2 subjects from 5 subjects?
\(\frac{5!}{3!}\)
\(\frac{5!}{2!2!}\)
\(\frac{5!}{2!3!}\)
\(\frac{5!}{2!}\)
Correct answer is C
A student can select 2 subjects from 5 subjects in;
5C3 ways, i.e. = \(\frac{5!}{2!(5 - 2)!}\)
= \(\frac{5!}{2!3!}\)
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
\(\sqrt{3}\)
2
3
\(\sqrt{2}\)
Correct answer is B
Let \(\delta^2\) and \(\delta\) denote the variance and standard deviation of the distribution respectively.
But \(\delta^2\) = 4 (given)
Hence \(\delta\) = \(\sqrt{4}\) = 2
25
30
35
20
Correct answer is A
N = \(\sum f\) = 15
Hence the median age is the \(\frac{N + 1}{2}\)th age, i.e.
\(\frac{15 + 1}{2}\)th = 8th
From the table, the age that falls on the 8th position when arranged in ascending order is 25years