From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected?
(A) 0.1
(B) 0.2
(C) 0.25
(D) 0.4
(E) 0.6
Ans:
This means that P(M and N both selected) = [spoiler](2/5) x (1/4) = 1/10[/spoiler]
Another question::
Joshua and Jose work at an auto repair center with 4 other workers. For a survey on health care insurance, 2 of the 6 workers will be randomly chosen to be interviewed. What is the probability that Joshua and Jose will both be chosen?
a)1/15
b)1/12
c)1/9
d)1/6
e)1/3
Ans:
[spoiler](1/6)*(1/5)+(1/6)*(1/5)=2/30=1/15[/spoiler]
Here why do we consider Both the options (Jose*Joshuna) and (Joshuna*jose)
But in the first question we considerded probability just 2/5x1/4 and why not (2/5x1/4)(1/4x2/5) like we did in the second problem.Please explain the difference..
Please explain
probability
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The second question can be solved using the exact same approach used in the first question.razaul karim wrote:From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected?
(A) 0.1
(B) 0.2
(C) 0.25
(D) 0.4
(E) 0.6
Ans:
This means that P(M and N both selected) = [spoiler](2/5) x (1/4) = 1/10[/spoiler]
Another question::
Joshua and Jose work at an auto repair center with 4 other workers. For a survey on health care insurance, 2 of the 6 workers will be randomly chosen to be interviewed. What is the probability that Joshua and Jose will both be chosen?
a)1/15
b)1/12
c)1/9
d)1/6
e)1/3
Ans:
[spoiler](1/6)*(1/5)+(1/6)*(1/5)=2/30=1/15[/spoiler]
Here why do we consider Both the options (Jose*Joshuna) and (Joshuna*jose)
But in the first question we considerded probability just 2/5x1/4 and why not (2/5x1/4)(1/4x2/5) like we did in the second problem.Please explain the difference..
Please explain
That is, P(Joshua and Jose both chosen) = (2/6) x (1/5) = 1/15
The solution you posted still has the correct answer (1/15). The only difference is that it considers two acceptable outcomes:
1) Joshua chosen 1st and Jose chosen 2nd
2) Jose chosen 1st and Joshua chosen 2nd
Cheers,
Brent
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I am not getting the solution. why is the probability of the first occurrence/selection 2/5 and not 1/5
When 2 events occur one after the other, we are suppose to multiply their probabilities.
The probability that Marnie is selected is 1/5
The probability that Noomi is selected is 1/4 (since only 4 employees are left)
so the probability that both Marnie and Noomi are selected is 1/5 * 1/4 = 1/20
This is the method used in one of the MGMAT practise test explanations.
Where am I going wrong?
When 2 events occur one after the other, we are suppose to multiply their probabilities.
The probability that Marnie is selected is 1/5
The probability that Noomi is selected is 1/4 (since only 4 employees are left)
so the probability that both Marnie and Noomi are selected is 1/5 * 1/4 = 1/20
This is the method used in one of the MGMAT practise test explanations.
Where am I going wrong?
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Our goal is to find P(M and N both selected)sanaa.rizwan wrote:I am not getting the solution. why is the probability of the first occurrence/selection 2/5 and not 1/5
When 2 events occur one after the other, we are suppose to multiply their probabilities.
The probability that Marnie is selected is 1/5
The probability that Noomi is selected is 1/4 (since only 4 employees are left)
so the probability that both Marnie and Noomi are selected is 1/5 * 1/4 = 1/20
This is the method used in one of the MGMAT practise test explanations.
Where am I going wrong?
There are two ways to approach this.
Method #1:
P(M and N both selected) = P(one of them is selected 1st AND the other selected 2nd)
= P(one of them is selected 1st) x P(the other selected 2nd)
= (2/5)(1/4)
= 1/10
Aside: P(one of them is selected 1st) = 2/5 because I'm allowing for either Marnie or Noomi to be selected first.
Method #2:
P(M and N both selected) = P(M selected 1st AND N selected 2nd OR N selected 1st AND M selected 2nd)
= P(M selected 1st AND N selected 2nd) + P(N selected 1st AND M selected 2nd)
= (1/5)(1/4) + (1/5)(1/4)
= 1/20 + 1/20
= 1/10
Both solutions yield the same answer.
Your approach, seems to consider one possible outcome (M selected 1st AND N selected 2nd) and doesn't consider the other one (N selected 1st AND M selected 2nd)
Cheers,
Brent
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There are a total of 5C2 = 5!/(3! x 2!) = (5 x 4)/2 = 10 ways of choosing two people from a group of five people. Since the selection of Marnie and Noomi corresponds to one of these choices, the probability of this selection is 1/10 = 0.1.razaul karim wrote:From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected?
(A) 0.1
(B) 0.2
(C) 0.25
(D) 0.4
(E) 0.6
Answer: A
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