Discussion
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- Question
In a box, there are four marbles of white color and five marbles of black color. Two marbles are chosen randomly. What is the probability that both are of the same color?
Options- A. 2/9
- B. 5/9
- C. 4/9
- D. 0
- Correct Answer
- 4/9
ExplanationNumber of white marbles = 4
Number of Black marbles = 5
Total number of marbles = 9
Number of ways, two marbles picked randomly = 9C2
Now, the required probability of picked marbles are to be of same color = 4C2/9C2 + 5C2/9C2
= 1/6 + 5/18
= 4/9.
- 1. Three dice are thrown together.Find the probability of getting a total of atleast 6.
Options- A. 103/216
- B. 103/108
- C. 103/36
- D. 36/103 Discuss
- 2. If an unbiased dice is rolled once, the odds in favour of getting a point which is multiple of 3 is:
Options- A. 1/2
- B. 2/1
- C. 1/3
- D. 3/1 Discuss
- 3. The probability that a bowler bowled a ball from a point will hit by the batsman is ¼. Three such balls are bowled simultaneously towards the batsman from that very point. What is the probability that the batsman will hit the ball ?
Options- A. 37/64
- B. 27/56
- C. 11/13
- D. 9/8 Discuss
- 4. The probability that a number selected at random from the first 100 natural numbers is a composite number is ?
Options- A. 3/2
- B. 2/3
- C. 1/2
- D. 34/7 Discuss
- 5. If x is chosen at random from the set {1,2,3,4} and y is to be chosen at random from the set {5,6,7}, what is the probability that xy will be even?
Options- A. 1/2
- B. 2/3
- C. 3/4
- D. 4/3 Discuss
- 6. Out of sixty students, there are 14 who are taking Economics and 29 who are taking Calculus. What is the probability that a randomly chosen student from this group is taking only the Calculus class ?
Options- A. 8/15
- B. 7/15
- C. 1/15
- D. 4/15 Discuss
- 7. In a simultaneous throw of two dice, what is the probability of getting a total of 7 ?
Options- A. 1/6
- B. 1/4
- C. 1/20
- D. 3/4 Discuss
- 8. A card is drawn from a pack of 52 cards. The probability of getting a queen of the club or a king of the heart is?
Options- A. 1/26
- B. 1/13
- C. 2/13
- D. 1/52 Discuss
- 9. Out of first 20 natural numbers, one number is selected at random. The probability that it is either an even number or a prime number is ?
Options- A. 16/19
- B. 1
- C. 3/2
- D. 17/20 Discuss
- 10. A brother and a sister appear for an interview against two vacant posts in an office. The probability of the brother?s selection is 1/5 and that of the sister?s selection is 1/3. What is the probability that only one of them is selected?
Options- A. 1/5
- B. 3/4
- C. 2/5
- D. 3/5 Discuss
Probability problems
Search Results
Correct Answer: 103/108
Explanation:
Total number of events=6 x 6 x 6=216
Let A be the event of getting a total of atleast 6 and B denoted event of getting a total of less than 6 i.e.,3,4,5.
So,B={(1,1,1),(1,1,2),(1,2,1),(2,1,1),(1,1,3),(1,3,1),(3,1,1),(1,2,2),(2,1,2),(2,2,1)}
Favourable number of cases=10
Therefore,P(B)=10/216
=> P(A) = 1 - P(B)
= 1 - (10/216) = 103/108
Correct Answer: 1/3
Explanation:
Total number =6
Getting a 'multiple of 3' = 2 . So, probability = 2/6 =1/3
Correct Answer: 37/64
Correct Answer: 3/2
Explanation:
The number of exhaustive events = 100 C? = 100.
We have 25 primes from 1 to 100.
Number of favourable cases are 75.
Required probability = 75/50 = 3/2.
Correct Answer: 2/3
Explanation:
S ={(1,5),(1,6),(1,7),(2,5),(2,6),(2,7),(3,5),(3,6),(3,7),(4,5),(4,6),(4,7)} xy will be even when even x or y or both will be even. P(E)=n(E)n(S)=812 = 4/3 |
Correct Answer: 7/15
Explanation:
Given total students in the class = 60
Students who are taking Economics = 24 and
Students who are taking Calculus = 32
Students who are taking both subjects = 60-(24 + 32) = 60 - 56 = 4
Students who are taking calculus only = 32 - 4 = 28
probability that a randomly chosen student from this group is taking only the Calculus class = 28/60 = 7/15.
Correct Answer: 1/6
Correct Answer: 1/26
Explanation:
Here in this pack of cards, n(S) = 52
Let E = event of getting a queen of the club or a king of the heart
Then, n(E) = 2
P(E) = n(E)/n(S) = 2/52 = 1/26
Correct Answer: 17/20
Explanation:
n(S) = 20
n(Even no) = 10 = n(E)
n(Prime no) = 8 = n(P)
P(E U P) = 10/20 + 8/20 - 1/20 = 17/20
Correct Answer: 2/5
Explanation:
Probability that only one of them is selected = (prob. that brother is selected) × (prob. that sister is not selected) + (Prob. that brother is not selected) × (Prob. that sister is selected)
= =
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