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- Question
- I forgot the last digit of a 7- digit telephone number. If I randomly dial the final 3 digits after correctly dialing the first four, then what is the chance of dialing the correct number?
Options- A. 1/1001
- B. 1/990
- C. 1/999
- D. 1/1000
- Correct Answer
- 1/1000
Explanationit is given that last 3 digits are randomly dialed
Then, each of the digit can be selected out of 10 digits in 10 ways. Hence, required probability
= 1/(10)3 = 1/1000 - 1. Three students are picked at random from a school having a total of 1000 students. The probability that these students will have identical date and month of their birth, is?
Options- A. 3/1000
- B. 3/365
- C. 1/(365)2
- D. None of these Discuss
- 2. If E be the set of all integers with 1 in their unit place. The probability that a number chosen {2, 3, 4,...50} is an elements of E, is?
Options- A. 5/49
- B. 4/49
- C. 3/49
- D. 2/49 Discuss
- 3. There are four machine and it is know that exactly two of them are faulty, They are tested. One by one in a random order till both the faulty machines are identified. Then the probability that only two tests are needed is?
Options- A. 1/3
- B. 1/6
- C. 1/2
- D. 1/4 Discuss
- 4. The probability that a card drawn from a pack of 52 cards will from a pack of 52 cards will be diamond or king being to?
Options- A. 4/52
- B. 4/13
- C. 1/52
- D. 2/13 Discuss
- 5. In suffling a pack of card 3 are accidentally dropped then the chance that missing card should be of different suit is?
Options- A. 169/425
- B. 261/425
- C. 104/425
- D. None of these Discuss
- 6. What is the probability that a non-leap year contains 52 Tuesday only?
Options- A. 1/7
- B. 2/7
- C. 3/7
- D. 6/7 Discuss
- 7. From a pack of 52 playing cards, two cards are drawn together at random. Calculate the probability of both the cards being king?
Options- A. 1/15
- B. 25/57
- C. 35/256
- D. None of these Discuss
- 8. In a bag containing three balls, a white ball was placed and then one ball was taken out at random. What is the probability that the extracted ball would turn on to be white, if all possible hypothesis concerning the colour of the balls that initially in the bag were equally possible?
Options- A. 5/8
- B. 3/4
- C. 1/2
- D. 3/8 Discuss
- 9. Raja can hit a target 3 times in 6 shots, Karan can hit the target 2 times in 6 shots and Ashwini can hit 4 times in 4 shots. What is the probability that atleast 2 shots hit the target?
Options- A. 1/2
- B. 2/3
- C. 1/3
- D. 5/6 Discuss
- 10. In his wardrobe, Girdhari has 3 trousers. One of them is grey the second blue and the third brown. In his wardrobe he also has 4 shirts. One of them is grey and the other 3 are white. He opens his wardrobe in the dark and pick out one shirt trouser pair without examination the color. What is the likelihood that neither the shirt nor the trouser is grey?
Options- A. 1/12
- B. 1/6
- C. 1/4
- D. 1/2 Discuss
Probability problems
Search Results
Correct Answer: 1/(365)2
Explanation:
Since, the 1st students can have any day as his birthday and according to the question corresponding to the 1st person and 2nd the 3rd person need to have the same day as their birthday and thus probability that they have identical birthday
= 1x (1/365) x (1/365)
= 1/(365)2
Correct Answer: 4/49
Explanation:
Favourable numbers are 11, 21, 31, 41.
? Required probability = 4/49
Correct Answer: 1/6
Explanation:
First we choose 1 machine out of the given 4 , the probability that it is faulty is 2/4 (favorable outcomes/possible outcomes)
Now we have to pick the second faulty machine the probability of doing so is 1/3.
Hence overall probability is 2/4 x 1/3 = 1/6
Correct Answer: 4/13
Explanation:
Total ways = 52
There are 13 cards of diamond, 4 cards of king, but one card is king of diamond which is counted both in diamond and king cards
? Favourable ways = 13 + 4 - 1 = 16
? Required probability = 16/52 = 4/13
Correct Answer: 169/425
Explanation:
Total ways 52C3 = 22100
There are 4 suit in a pack of cards so three suit can be selected in 4C3 ways.
One card each from different unit can selected as = 13C1 X 13C1 X 13C1 ways
So, favourable ways = 4C3 X 13C1 X 13C1 X 13C1 = 8788
? Required probability = 8788/22100 = 169/425
Correct Answer: 6/7
Explanation:
A non-leap year has 365 days, each day repeats for 52 times with 1 day left
This one can be {Sun, Mon, Wed, Thu, Fri, and Sat}.
? p = 6/7
Correct Answer: None of these
Explanation:
Two cards can be drawn from a pack of 52 playing cards in 52C2 ways. i,e., 52 x 51 / 2 = 1326 ways. The event that two kings appear in a single drawn of cards is 4C2 ways, i.e 6 ways.
? The probability that the two cards drawn from a pack of 52 cards are kings = 6/1326 = 1/221
Correct Answer: 5/8
Explanation:
Since, all possible hypothesis regarding the colour of the balls are equally likely, therefore these could be 3 white balls, initially in the bag.
? Required probability = 1/4 [1 + 3/4 + 1/2 + 1/4]
= 1/4 [(4 + 3 + 2 + 1)/4] = 5/8
Correct Answer: 2/3
Explanation:
Ashwini hits the target definitely, hence required probability that atleast 2 shots hit the target is given by
Karan hits tha target and Raja not hit the target.
or
Karan does not hit the target and Raja hits the target.
or.
Karan hits the target and Raja hits the target
= 2/6 x 3/6 + 4/6 x 3/6 + 2/6 x 3/6
= 24/36 = 2/3
Correct Answer: 1/2
Explanation:
Probability that trouser is not grey = 2/3
Probability that shirt is not grey = 3/4
? Required probability = 2/3 x 3/4 = 1/2
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