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Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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Finding the probability of obtaining exactly 2 Red colors and 2 Blue colors is the best way to find the solution, after which we can subtract the answer from 1.

The probability of acquiring

Red color = 5/10 = 1/2

Probability of acquiring

Blue color = 3/10

Select which 2 out of 4 rounds will be Red: C(4,2) = 6 solutions

For any combination: (1/2)^2 * (3/10)^2 = 9/400

Totaling: 6 * 9/400 = 54/400 = 27/200

Thus, we acquire the probability of getting 2 Red colors and 2 Blue colors.

Thus: 1 - 27/200 = 173/200

Option D
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p(exactly 2r, 2b) = 4 combination 3 × (5/10)2 × (3/10)2
= 6 × (1/2)2 × (3/10)2
= 6 × 1/4 × 9/100
= 27/200
q asks for not this event, so we use cp
cp = 1 − 27/200 = 173/200
ans: d (173/200)


Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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So we assuming we have 5 red balls and 3 blue and 2 green. We are picking 4 balls at random. Once the ball is picked the ball is again added to collection or box and then a new ball is picked.

So probability of not picking combination of 2 red and 2 blue balls is 1- p(2R,2B)

p(R) = 1/2
p(B) = 3/10

and there are combinations of receiving the balls at different turns i.e 4C2 = 6

So p(2R2B) = (1/2)^2 * (3/10)^2 * 6 = 27/200
ans = 1 - 27/200 = 173/200

Ans = D
Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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Here's my solution for this question
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Probably one of the easiest question in today's set -
For each round we have 5 Red and 3 Green guys available to be chosen
So, for exactly 2 guys of Red and Green be chosen the prob is =
5/10 * 5/10 * 3/10 * 3/10 ( because every round all the participants are eligible ) = 9/400

Now we need to find what is the remaining prob ie.these students should not repeat twice
Hence = 1 - 9/400 = 391/400 Ans
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Since we have 4 groups each with a pool of 10 to chose from, then the total count is 10^4= 10000
The undesired outcome is exactly 2 from Red and exactly 2 from Blue
Probability of picking from Red is 5/10, from Blue is 3/10 and 2/10 from green
Sequence with exactly 2 reds and 2 blues
Choose 2 positions from 4 4C2= 6
2 blue and 2 red 9 (R,R,B,B)= 5/10X5/10X3/10X3/10=9/400X6 = 27/200 (Undesired)
Desired event is 1-undesired
1-27/200= 173/200
Ans D
Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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Red 5
Blue 3
Green 2

2 Red and 2 Blue combine in 4!/(2!*2!) = 6 ways

Each way has a probability of (5/10)^2 * (3/10)^2 = (1/2)^2 * (3/10)^2 = 1/4 * 9/100 = 9/400

6 * 9/400 = 54/400 = 27/200 -> probability of getting 2 Red and 2 Blue

Not getting 2 Red and 2 Blue -> 1-27/200 = 173/200

IMO D
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10 contestants -> 3 teams
Team red -> 5 contestant
Team blue -> 3 contestant
Team green -> 2 contestant

4 rounds -> each round 1 contestant chosen from 10

Find probability where in 4 choice, 2 red contestant and 2 blue contestant not chosen

So,
Total number of outcomes = 10^4 = 10000
Possibilities where 2 red and 2 blue chosen = 4C2 * (5^2) * (3^2) = 6*25*9 = 1350
Probability (2 Red & 2 Blue) = 1350/10000 = 27/200
P(Not 2 Red & 2 Blue) = 1 - 27/200 = 173/200

D. 173/200
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P(R) = 5/10==> 1/2
P(B)= 3/10
P(G)=2/10 ==> 1/5
Needed : 1- exactly 2 R and 2 B
for exactly 2R and 2B :
from the 4 rounds lets first take which 2 will be Red the remaining 2 will automatically be blue ==4C2 =6
now (1/2)^2 * (3/10)^2 = 9/400
since 6 possible cases as earlier counted ===6* 9/400 = 54/400
1-54/400 = 173/200
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N(total) = 10*10*10*10
N(2R and 2B) = 4C2 * 5^2 * 3^2 =1350


P (not 2R and 2B) = (10000-1350)/10000 =173/200

(D) is the answer
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Team Red: 5
Team Blue: 3
Team Green: 2

probability 4 choices are not made up of exactly 2 from Team Red and exactly 2 from Team Blue = 1 - probability 4 choices are made up of exactly 2 from Team Red and exactly 2 from Team Blue

p(Red in one choice)=5/10=1/2
p(Blue in one choice)=3/10

Red and Blue can be choosen: 4!/(2!*2!) = 24/4 = 6 options

p(2 Red and 2 Blue) = 6*(1/2)^2*(3/10)^2 = 54/400 = 27/200
p(no 2 Red and 2 Blue) = 1-27/200 = 173/200

Answer D
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Probability of the complementary event can be calculated easier.
Complementary event: choose exactly 2 red and 2 blue.

How many ways of doing this: 4C2 = 6
Probability of one arrangement: (5/10)^2*(3/10)^2 = 9/400

Probability = 6*9/400 = 3*9/200 = 27/200

Probability complementary event = 1 - 27/200 = 173/200

The answer is D
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Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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Probability of getting exactly 2 red and exactly 2 blue = 5/10*5/10*3/10*3/10 = 9/400
Total number of such arrangements possible = 4!/2!*2! = 6
Thus, total probability becomes = 54/400

Probability of not getting 2 red and 2 blue = 1 - 54/400 = 346/400 = 173/200. Answer is D.
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Option D - 173/200

Sol
Total contestants = 10
3 teams - Red , Blue and Green
Red = 5
Blue = 3
green = 2

Probability of Red = 5/10 = 1/2
P Blue = 3/10
P Green= 2/10 = 1/5

Fining P of 2 contestants from team red and exactly 2 contestants from team blue

Number of arrangement for 2 R and 2 B = ( R,R,B,B) = (4
2)
So 4!/2!2! = 6 ways

P of any single arrangement = P(R)xP(R)xP(B)xP(B)
= 1/2x1/2x3/10x3/10
= 9/400

Total P = 6x 9/400 = 27/200
So the P that 2 contestants are Not from 2 red and 2 blue = 1-27/200

= 173/200




Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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The question asked: Probability of NOT EXACTLY 2 Red and 2 Blue?

To answer: we can calculate P (Not Exactly 2 Red, 2 Blue) = 1 - P (Exactly 2 Red, 2 Blue)

Probability = Favorable outcome / Total outcome

First, calculate the total outcome
10 contestants -> 4 Rounds -> 10 x 10 x 10 x 10 = 10^4 = 10.000

Second, calculate the fav outcome

2 RED, 2 BLUE -> means, 0 Green

For 4 rounds -> 4 C 2 = 6
For 2 Reds out of 5 Red Contestants -> 5 X 5 = 5^2 = 25
For 2 Blue out of 3 Blue Contestants -> 3 x 3 = 3^2 = 9
Total -> 6*25*9 = 1.350

Third, calculate Probability for Exactly 2R, 2B
1350 / 10.000 = 135 / 1000 = 27 / 200

Fourth, calculate Probability for NOT Exactly 2R, 2B
1 - 27/200 = 173/200 (Answer D)
Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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R=5, B=3 and G=2

p(R)=1/2
p(B)=3/10
p(G)=1/5

if 2R and 2B then p = (1/2)^2*(3/10)^2 = 9/400

there are 4C2 = 6 ways -> p = 6*9/400 = 54/400 = 27/200

the question ask probability of "not made": 1-27/200 = 173/200

The correct answer is D
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IMO ans is E 391 /400
1 -(.5)^2 (.3)^2 = 391/400 easy one.

Bunuel
At a quiz show, 10 contestants are divided into 3 teams: Team Red has 5 contestants, Team Blue has 3 contestants, and Team Green has 2 contestants. The show has 4 rounds, and in each round, 1 contestant is chosen at random from all 10 contestants. If a contestant chosen in one round remains eligible to be chosen again in any later round, what is the probability that the 4 choices are not made up of exactly 2 contestants from Team Red and exactly 2 contestants from Team Blue?

A. 27/200
B. 1/7
C. 6/7
D. 173/200
E. 391/400


 


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