T=2
t^2=4
4-4=0
is that right?
Answer:
A.1/12
Step-by-step explanation:
Probability of the card being yellow is 1/4
And probability of the card being even is 1/3
And if you are asked to find a yellow even card we multiply those two numbers to get 1/12
Answer:
The variance of these investment returns is 74
Step-by-step explanation:
Given:
Series = 10, 30, 15, 5, 20
To Find:
variance of a series = ?
Solution:
The variance of the series = 
Now 
= 
= 36 + 196 +121 + 1+ 16
= 370
Now
= 74
Notice that
(1 + <em>x</em>)(1 + <em>y</em>) = 1 + <em>x</em> + <em>y</em> + <em>x y</em>
So we can add 1 to both sides of both equations, and we use the property above to get
<em>a</em> + <em>b</em> + <em>a b</em> = 76 ==> (1 + <em>a</em>)(1 + <em>b</em>) = 77
and
<em>c</em> + <em>d</em> + <em>c d</em> = 54 ==> (1 + <em>c</em>)(1 + <em>d</em>) = 55
Now, 77 = 7*11 and 55 = 5*11, so we get
<em>a</em> + 1 = 7 ==> <em>a</em> = 6
<em>b</em> + 1 = 11 ==> <em>b</em> = 10
(or the other way around, since the given relations are symmetric)
and
<em>c</em> + 1 = 5 ==> <em>c</em> = 4
<em>d</em> + 1 = 11 ==> <em>d</em> = 10
Now substitute these values into the desired quantity:
(<em>a</em> + <em>b</em> + <em>c</em> + <em>d</em>) <em>a</em> <em>b</em> <em>c</em> <em>d</em> = 72,000
800+16x=720+21x
80+16x=21x
80=5x
X=16
So 16 hours :)
