probability problems Practice Question and Answer
7 Q: A school has 45% girls. If 80% of girls score more than 75% marks and 70% of the boys have score more than 75% marks. If a student is selected at random and is found to have more than 75% marks, find the probability of it being a boy.
393 064dc7c18d02c5c746bf45d36
64dc7c18d02c5c746bf45d36- 177/149true
- 275/149false
- 3Cannot be determinedfalse
- 411/20false
- 59/20false
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Answer : 1. "77/149"
Q: A person can hit a target 5 times out of 8 shots. If he fires 10 shots, what is the probability that he will the target twice?
790 064b4f3e1e154aff5337290bd
64b4f3e1e154aff5337290bd- 1$${1135×3^8}\over 8^{10} $$false
- 2$${1165×3^8}\over 8^{10} $$false
- 3$${1175×3^8}\over 8^{10} $$false
- 4$${1125×3^8}\over 8^{10} $$true
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Answer : 4. " $${1125×3^8}\over 8^{10} $$"
Q: A speaks the truth 5 out of 7 times and B speaks truth 8 out of 9 times. What is the probability that they contradict each other in stating the same fact?
669 064abe46765d2524cbf2197ca
64abe46765d2524cbf2197ca- 1$${1\over 7}$$false
- 2$${1\over 9}$$false
- 3$${1\over 4}$$false
- 4$${1\over 3}$$true
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Answer : 4. "$${1\over 3}$$"
Q: The probabilities of solving a problem by three students A, B and C are $$3\over 7$$, $$5\over 9$$ and $$1\over 5$$ respectively. The probability that problem will be solved is:
442 0649e770dab3c5fffc2ee1c4c
649e770dab3c5fffc2ee1c4c- 1$$155\over 315$$false
- 2$$64\over 315$$false
- 3$$251\over 315$$true
- 4$$32\over 315$$false
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Answer : 3. "$$251\over 315$$"
Q: In a box there are 6 blue ball, X red balls & 10 green balls. Probability of choosing one red ball from the given box is $$ {1\over 3}$$. Then find the sum of red and blue balls in the box?
881 0619f577cd129fc6243ae369b
619f577cd129fc6243ae369b- 120false
- 212false
- 314true
- 418false
- 516false
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Answer : 3. "14"
Q: A box contains 10 red ball, 6 green ball if 2 balls are drawn randomly what is the probability of getting non-green ball?
1039 06093819d12ecca62c6c812d3
6093819d12ecca62c6c812d3- 1$${5\over16}$$false
- 2$${16\over55}$$false
- 3$${3\over8}$$true
- 4$${5\over8}$$false
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Answer : 3. "$${3\over8}$$ "
Q: A bag contains 3 white balls and 2 black balls. Another bag contains 2 white and 4 black balls. A bag and a ball are picked random. The probability that the ball will be white is:
925 0608be26c5c992217d5822aff
608be26c5c992217d5822aff- 17/15false
- 29/16false
- 34/15false
- 43/5true
- 58/5false
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