The probability of Sam passing the exam is 1/4. The probability of Sam passing the exam and Michael passing the driving test is 1/6.What is the probability of Michael passing his driving test?
Answer(s): D
Indicate A as the probability of Michael passing the driving test.The probability of Sam passing the test is 1/4, the probability of both events happening together is 1/6 so: 1/4 x A = 1/6 therefore A = 2/3.
In a blue jar there are red, white and green balls. The probability of drawing a red ball is 1/5. The probability of drawing a red ball, returning it, and then drawing a white ball is 1/10. What is the probability of drawing a white ball?
Answer(s): B
Indicate A as the probability of drawing a white ball from the jar. The probability of drawing a red ball is 1/5. The probability of drawing both events is 1/10 so, 1/5 x A = 1/10. Therefore, A = ½.
Out of a classroom of 6 boys and 4 girls the teacher picks a president for the student board, a vice president and a secretary. What is the probability that only girls will be elected?
Answer(s): C
The basic principle of this question is that one person can’t be elected to more than one part, therefore when picking a person for a job the “inventory” of remaining people is growing smaller.The probability of picking a girl for the first job is 4/10 = 2/5.The probability of picking a girl for the second job is (4-1)/(10-1) = 3/9. The probability of picking a girl for the third job is (3-1)/(9-1) = 1/4.The probability of all three events happening is: 2/5 x 3/9 x ¼ = 1/30.
Two dice are rolled. What is the probability the sum will be greater than 10?
When rolling two dice, there are 36 possible pairs of results (6 x 6).A sum greater than 10 can only be achieved with the following combinations: (6,6), (5,6), (6,5). Therefore, the probability is 3/36 = 1/12.
The probability of having a girl is identical to the probability of having a boy. In a family with three children, what is the probability that all the children are of the same gender?
Answer(s): E
The gender of the first-born is insignificant since we want all children to be of the same gender no matter if they are all boys or girls.The probability for the second child to be of the same gender as the first is: ½. The same probability goes for the third child. Therefore, the answer is ½ x ½ = ¼.
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