(X/3) - 8 = 12
X being a number divided by 3. This part in parentheses so you solve it first. Subtract 8 from that and your answer equals 12.
Answer:Given:
P(A)=1/400
P(B|A)=9/10
P(B|~A)=1/10
By the law of complements,
P(~A)=1-P(A)=399/400
By the law of total probability,
P(B)=P(B|A)*P(A)+P(B|A)*P(~A)
=(9/10)*(1/400)+(1/10)*(399/400)
=51/500
Note: get used to working in fraction when doing probability.
(a) Find P(A|B):
By Baye's Theorem,
P(A|B)
=P(B|A)*P(A)/P(B)
=(9/10)*(1/400)/(51/500)
=3/136
(b) Find P(~A|~B)
We know that
P(~A)=1-P(A)=399/400
P(~B)=1-P(B)=133/136
P(A∩B)
=P(B|A)*P(A) [def. of cond. prob.]
=9/10*(1/400)
=9/4000
P(A∪B)
=P(A)+P(B)-P(A∩B)
=1/400+51/500-9/4000
=409/4000
P(~A|~B)
=P(~A∩~B)/P(~B)
=P(~A∪B)/P(~B)
=(1-P(A∪B)/(1-P(B)) [ law of complements ]
=(3591/4000) ÷ (449/500)
=3591/3592
The results can be easily verified using a contingency table for a random sample of 4000 persons (assuming outcomes correspond exactly to probability):
===....B...~B...TOT
..A . 9 . . 1 . . 10
.~A .399 .3591 . 3990
Tot .408 .3592 . 4000
So P(A|B)=9/408=3/136
P(~A|~B)=3591/3592
As before.
Step-by-step explanation: its were the answer is
Answer:
3 a : 2 b = 6 : 1
Step-by-step explanation:
<em>
= 
</em>
<em>3 ( a + b) = 5 ( a - b)
</em>
<em>3 a + 3 b = 5 a - 5 b
</em>
<em>5 b + 3 b = 5 a - 3 a
</em>
<em>
8 b = 2 a
</em>
<em>
2 a = 8 b</em>
<em><u>a = 4 b</u></em>
<em>3 a = 3 × 4 b</em>
<em><u>3 a = 12 b</u></em>
<em>3 a: 2 b = 12 b : 2 b</em>
<em>3 a : 2 b = 6 : 1</em>
-8, 3 Do you need me to explain
