192 people were survey
Step-by-step explanation:
The given is:
- 85% of the people survey thought the price of the car wash was reasonable
- 164 people thought the cost of the car wash was reasonable
We need to find how many people were survey
Assume that x people were survey
∵ There were x people survey
∵ 85% of them thought the price of the car wash was reasonable
∴ The number of the people who thought the price of the car wash
was reasonable = 85% × x
∵ 85% = 
= 0.85
∴ The number of the people who thought the price of the car wash
was reasonable = 0.85 x
∵ 164 people thought the cost of the car wash was reasonable
- Equate 0.85 x and 164
∴ 0.85 x = 164
- Divide both sides by 0.85
∴ x = 192.94
∵ x represents a number of people, then it must be integer
∴ The number of people were survey = 192
192 people were survey
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2v=3-7
2v=-4 divide both sides
v=-2
16 students is the correct answer...
for every 5 boys there are 3 girls, so 20 boys 6 girls = the total of 16 students
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
