In how many ways can 9 people be seated if 3 chairs are available?
720
504
336
210
Correct answer is B
| 9P3 = | _9! | ways |
| (9-3)! |
| = | 9! |
| 6! |
| = | 9x8x7x6! |
| ___6! |
= 504 ways
15
28
30
45
Correct answer is D
No explanation has been provided for this answer.
What is the mean deviation of x, 2x, x+1 and 3x. If their mean is 2?
0.5
1.0
1.5
2.0
Correct answer is A
| x | ∴x | x-X | /x-X/ |
| x | 1 | -1 | 1 |
| 2x | 2 | 0 | 0 |
| x+1 | 2 | 0 | 0 |
| 3x | 3 | 1 | 1 |
| ∑/x-X/=2 |
| Mean = | x+2x+x+1+3x |
| ____4 |
| 2 = | 7x+1 |
| _4 |
8 = 7x+1
7x = 8-1
7x = 7
x = 1
| Mean deviation = | ∑/x-X/ |
| __n |
| = | 2 |
| 4 |
| = | 1 |
| 2 |
= 0.5
4
3
2
1
Correct answer is C
| x | f | fx | |
| 5 | 3 | 15 | |
| 8 | 2 | 16 | |
| 6 | 4 | 24 | |
| k | i | k | |
| ∑f=10 | ∑fx=55+k |
| Mean = | ∑fx |
| ∑fx |
| 5.7 = | 55+k |
| 10 |
57 = 55 + k
k = 57 - 55
k = 2
2/3
4/9
8/27
1/27
Correct answer is D
P(pass) = 2/3
P(not pass) = 1 - 2/3 = 1/3
P(not passing any of the 3 Exams) = 1/3 x 1/3 x 1/3
= 1/27