Find the variance of 2x, 2x-1 and 2x+1
2/3
2
√(2/3)
1
Correct answer is A
No explanation has been provided for this answer.
8
10
4
6
Correct answer is D
Black = 5
White = 4
Red = x
Total = 9+x
P(red) = 2/3
x / (9+x) = 2/5
5x = 2(9+x)
5x = 18+2x
5x-2 = 18
3x = 18
x = 6
If the mean of five consecutive integers is 30, find the largest of the numbers
28
30
32
34
Correct answer is C
Let the consecutive numbers be a, a+1, a+2, a+3, a+4
Mean = \(\frac{(a+a+1+a+2+a+3+a+4)}{5}\\
30 = \frac{5a+10}{5}\\
30 \times 5 = 5a + 10\\
5a = 150 - 10\\
5a = 140\\
a = 28 \\
∴ a + 4 = 28 + 4\\
= 32\)
15
20
30
45
Correct answer is A
The question will be answered in
\(^5C_4 = \frac{6!}{(6-4)!4!}\\=\frac{6!}{2!4!}\\=\frac{6\times5\times4!}{2\times1\times4!}\\=15\hspace{1mm}ways\)
1/20
1/3
3/20
7/10
Correct answer is C
U = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20}
A = {x/x is divisible by 2}
A = {2,4,6,8,10,12,14,16,18,20}
B = {x/x is divisible by 3}
A ∩ B = {6, 12, 18}
P(Number divisible by both 2 and 3)
= 3/20