probability questions with solutions - Wikitechy https://www.wikitechy.com/interview-questions/tag/probability-questions-with-solutions/ Interview Questions Mon, 06 Sep 2021 06:42:30 +0000 en-US hourly 1 https://wordpress.org/?v=6.9 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png probability questions with solutions - Wikitechy https://www.wikitechy.com/interview-questions/tag/probability-questions-with-solutions/ 32 32 Four whole number taken at random are multiplied together. The chance that the last digit of the product is 1, 3, 7, or 9 is ? https://www.wikitechy.com/interview-questions/probability/four-whole-number-taken-at-random-are-multiplied-together-the-chance-that-the-last-digit-of-the-product-is-1-3-7-or-9-is/ https://www.wikitechy.com/interview-questions/probability/four-whole-number-taken-at-random-are-multiplied-together-the-chance-that-the-last-digit-of-the-product-is-1-3-7-or-9-is/#respond Wed, 18 Aug 2021 02:12:01 +0000 https://www.wikitechy.com/interview-questions/?p=2052

Four whole number taken at random are multiplied together. The chance that the last digit of the product is 1, 3, 7, or 9 is ?

A. 16/625

B. 1/210

C. 8/125

D. 4/25

Answer : A. 16/625

Explanation:

  • Since the product has to end in 1, 3, 7 or 9, the units place of all the 4 numbers we want to multiply can’t end in 0, 2, 4, 5, 6, 8. That means it can only end in 1, 3, 7, 9.
  • This means that the probability of selecting one number that ends in 1, 3, 7 or 9 is 4/10 = 2/5.
  • Therefore the probability of selecting four numbers that end in 1, 3, 7 or 9 is (2/5) x (2/5) x (2/5) x (2/5) = 16/625.
  • Hence, the probability of selecting 4 numbers such that their product ends in 1, 3, 7 or 9 is 16/625.
]]> https://www.wikitechy.com/interview-questions/probability/four-whole-number-taken-at-random-are-multiplied-together-the-chance-that-the-last-digit-of-the-product-is-1-3-7-or-9-is/feed/ 0 A brother and sister appear for an interview against two vacant posts in an office. The probability of the brother’s selection is 1/5th and that of the sister’s selections is 1/3rd. What is the probability that one of them is selected ? https://www.wikitechy.com/interview-questions/probability/a-brother-and-sister-appear-for-an-interview-against-two-vacant-posts-in-an-office-the-probability-of-the-brothers-selection-is-1-5th-and-that-of-the-sisters-selections-is-1-3rd-what-is-the-prob/ https://www.wikitechy.com/interview-questions/probability/a-brother-and-sister-appear-for-an-interview-against-two-vacant-posts-in-an-office-the-probability-of-the-brothers-selection-is-1-5th-and-that-of-the-sisters-selections-is-1-3rd-what-is-the-prob/#respond Wed, 18 Aug 2021 02:10:04 +0000 https://www.wikitechy.com/interview-questions/?p=2051

A brother and sister appear for an interview against two vacant posts in an office. The probability of the brother’s selection is 1/5th and that of the sister’s selections is 1/3rd. What is the probability that one of them is selected ?

A. 1/5

B. 2/5

C. 1/3

D. 2/3

Answer : B. 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)

Hence, Required Probability = 1/5 x 2/3 + 4/5 x 1/3
= 2/15 + 4/15
= 6/15
= 2/5.

]]> https://www.wikitechy.com/interview-questions/probability/a-brother-and-sister-appear-for-an-interview-against-two-vacant-posts-in-an-office-the-probability-of-the-brothers-selection-is-1-5th-and-that-of-the-sisters-selections-is-1-3rd-what-is-the-prob/feed/ 0 A bag contains 8 red and 5 white balls. 2 balls are drawn at random. What is the probability that both are white ? https://www.wikitechy.com/interview-questions/probability/a-bag-contains-8-red-and-5-white-balls-2-balls-are-drawn-at-random-what-is-the-probability-that-both-are-white/ https://www.wikitechy.com/interview-questions/probability/a-bag-contains-8-red-and-5-white-balls-2-balls-are-drawn-at-random-what-is-the-probability-that-both-are-white/#respond Wed, 18 Aug 2021 02:08:13 +0000 https://www.wikitechy.com/interview-questions/?p=2050

A bag contains 8 red and 5 white balls. 2 balls are drawn at random. What is the probability that both are white ?

A. 5/16

B. 2/13

C. 3/26

D. 5/39

Answer : D. 5/39

Explanation:

  • n(S) = Number of methods for drawing 2 balls out of 13 = 13C2
    = (13 x 12) / 2
    = 78.
  • n(E) = No. of methods for drawing 2 balls out of 5 = 5C2
    = (5 x 4) / 2
    = 10.
  • Therefore, P(E) = n(E) / n(S)
    = 10/78
    = 5/39.
]]> https://www.wikitechy.com/interview-questions/probability/a-bag-contains-8-red-and-5-white-balls-2-balls-are-drawn-at-random-what-is-the-probability-that-both-are-white/feed/ 0 The probability of drawing a red card from a deck of playing cards is ? https://www.wikitechy.com/interview-questions/probability/the-probability-of-drawing-a-red-card-from-a-deck-of-playing-cards-is/ https://www.wikitechy.com/interview-questions/probability/the-probability-of-drawing-a-red-card-from-a-deck-of-playing-cards-is/#respond Wed, 18 Aug 2021 02:03:23 +0000 https://www.wikitechy.com/interview-questions/?p=2048

The probability of drawing a red card from a deck of playing cards is ?

A. 2/18

B. 1/13

C. 1/4

D. 1/2

Answer : D. 1/2

Explanation:

Total number of cards n(S) = 52
Number of red cards n(E) = 26.
Hence, P(E) = n(E) / n(S)
= 26/52
= 1/2.

]]> https://www.wikitechy.com/interview-questions/probability/the-probability-of-drawing-a-red-card-from-a-deck-of-playing-cards-is/feed/ 0 If the probability that A will live 15 year is 7/8 and that B will live 15 year is 9/10, then what is the probability that both will live after 15 year ? https://www.wikitechy.com/interview-questions/probability/if-the-probability-that-a-will-live-15-year-is-7-8-and-that-b-will-live-15-year-is-9-10-then-what-is-the-probability-that-both-will-live-after-15-year/ https://www.wikitechy.com/interview-questions/probability/if-the-probability-that-a-will-live-15-year-is-7-8-and-that-b-will-live-15-year-is-9-10-then-what-is-the-probability-that-both-will-live-after-15-year/#respond Wed, 18 Aug 2021 02:01:31 +0000 https://www.wikitechy.com/interview-questions/?p=2047

If the probability that A will live 15 year is 7/8 and that B will live 15 year is 910, then what is the probability that both will live after 15 year ?

A. 1/20

B. 63/80

C. 1/5

D. None of these

Answer : B. 63/80

Explanation:

P(A) = 7/8, P(B) = 9/10
Required Probability = P(A) x P(B)
= (7/8) x (9/10)
= 63/80.

]]> https://www.wikitechy.com/interview-questions/probability/if-the-probability-that-a-will-live-15-year-is-7-8-and-that-b-will-live-15-year-is-9-10-then-what-is-the-probability-that-both-will-live-after-15-year/feed/ 0 A card is drawn from a well-shuffled pack of cards. The probability of getting a queen of club or king of the heart is ? https://www.wikitechy.com/interview-questions/probability/a-card-is-drawn-from-a-well-shuffled-pack-of-cards-the-probability-of-getting-a-queen-of-club-or-king-of-the-heart-is/ https://www.wikitechy.com/interview-questions/probability/a-card-is-drawn-from-a-well-shuffled-pack-of-cards-the-probability-of-getting-a-queen-of-club-or-king-of-the-heart-is/#respond Wed, 18 Aug 2021 01:59:34 +0000 https://www.wikitechy.com/interview-questions/?p=2046

A card is drawn from a well-shuffled pack of cards. The probability of getting a queen of club or king of the heart is ?

A. 1/52

B. 1/26

C. 1/13

D. None of these

Answer : B. 1/26

Explanation:

n(S) = 52.
Let E = Event of getting a queen of club or a king of heart.
Then, n(E) = 2.
P(E) = n(E) / n(S)
= 2 / 52
= 1 / 26

]]> https://www.wikitechy.com/interview-questions/probability/a-card-is-drawn-from-a-well-shuffled-pack-of-cards-the-probability-of-getting-a-queen-of-club-or-king-of-the-heart-is/feed/ 0 A letter is chosen at random from the word ‘ASSASSINATION’. What is the probability that it is a consonant ? https://www.wikitechy.com/interview-questions/probability/a-letter-is-chosen-at-random-from-the-word-assassination-what-is-the-probability-that-it-is-a-consonant/ https://www.wikitechy.com/interview-questions/probability/a-letter-is-chosen-at-random-from-the-word-assassination-what-is-the-probability-that-it-is-a-consonant/#respond Wed, 18 Aug 2021 01:39:18 +0000 https://www.wikitechy.com/interview-questions/?p=2027

A letter is chosen at random from the word “ASSASSINATION”. What is the probability that it is a consonant ?

A. 4/13

B. 8/13

C. 7/13

D. 6/13

Answer : C. 7/13

Explanation:

Total Number of letters in the word ASSASSINATION, n(S) = 13
Total number of consonants in the word ASSASSINATION = 7 (i.e., {S, S, S, S, N, T, N }
P(consonant) = 7/13

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