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11.
A box contains 4 red balls, 5 green balls and 6 white balls. A ball is drawn at random from the box. What is the probability that the ball drawn is either red or green?
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A.
2 5 -
C.
1 5
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B.
3 5 -
D.
7 15
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
Total number of balls = (4 + 5 + 6) = 15 | |||||||||||||||||||||
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12.
What is the probability of getting atleast on head from 3 tosses of a coin?
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A.
11 8 -
C.
5 8
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B.
7 8 -
D.
3 8
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
When 3 coins are tossed the sample space is given by 2 x 2 x 2 = 8 | ||||||||
The favourable case is getting atleast one head (i.e) 1,2 or 3 heads (or) tail should not occur in all the 3 coins simultaneously. | ||||||||
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13.
Three unbiased coins are tossed. What is the probability of getting at least 2 heads?
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A.
1 4 -
C.
1 3
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B.
1 2 -
D.
1 8
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH} | |||||||||||||||||
Let E = Event of getting at least two heads = {THH, HTH, HHT, HHH} | |||||||||||||||||
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14.
In a box there are 6 blue, 6 red, 6 white and 6 black balls. Four balls are picked up randomly. What is the probability that all the four balls may not be blue?
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A.
10625 10626 -
C.
203 204
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B.
3735 3542 -
D.
3537 3542
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
Total no. of balls = 24 | |||||||||||||
Total no. of cases of selecting 4 balls = 24C4 | |||||||||||||
Total no. of ways of selecting all blue balls = 6C4 | |||||||||||||
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15.
Two cards are drawn from a pack of 52 cards. The probability that either both are red or both are kings, is:
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A.
7 13 -
C.
63 221
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B.
3 26 -
D.
55 221
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
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Let E1 = event of getting both red cards, | |||||||||||||||||||||||||||
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Then, E1 ∩ E2 = event of getting 2 kings of red cards. | |||||||||||||||||||||||||||
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n(E1 ∩ E2) = 2C2 = 1 | |||||||||||||||||||||||||||
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