Introduction to Probability

1. A fair coin is tossed 100 times. The results are 46 heads and 54 tails. What is the probability that the next toss is heads?

  P(A) = 0.460
  P(A) = 0.540
  P(A) = 1.000
  P(A) = 0.500

2.Which of the following answers can represent the probability of an event occurring?
  P(A) = 0.524
  P(A) = 1.414
  P(A) = sqrt(5)
  P(A) = -0.147

3. A couple decides that they want to have 4 children. What is the probability that they have at least 3 girls?

  P(A) = 0.625
  P(A) = 0.313
  P(A) = 0.500
  P(A) = 0.725

4. Construct the sample space for rolling a pair of dice. What is the probability of rolling doubles?

  P(A) = 0.167
  P(A) = -0.167
  P(A) = 0.833
  P(A) = 0.333

5. As part of an in class experiment, students tossed a fair coin 100 times and recorded their results. They were then asked to determine the probability of heads, based on the in class experiment. What type of probability did they use?

  Classical Probability
  Relative Frequency
  Subjective
  No probability was used at all

6.The sample space for rolling a single die is {1, 2, 3, 4, 5, 6}. Which of the sets below represents the complement to the event A = {1, 2, 4}?

  {1, 2, 3}
  {3, 5, 6}
  {2, 4, 6}
  {2, 3, 5}

7.The question above had 4 responses. Assuming you guessed at the answer (yes, I know that is a silly assumption but go with me on this one) what is the probability that you got the question correct?

  P(A) = 0.500.
  P(A) = 1.000.
  P(A) = 0.200.
  P(A) = 0.250.

8.When teaching Statistics one semester, an instructor's grade distribution was as follows: 7 A's, 10 B's, 8 C's, 2 D's and 3 F's. If a student is selected at random, what is the probability that the student received an A?

  P(A) = 0.500
  P(A) = 0.767
  P(A) = 0.233
  P(A) = 0.358

9. In her August 10, 1997 column for Parade magazine, Marilyn vos Savant was posed the question "Your dog has a litter of four, is it most likely that two are males and two are females?" That is, is the most likely outcome having exactly 2 boys and 2 girls. Using probability theory, is the answer yes or no? Assume male and female births are equally likely, (she did) and if you need a hint, see question 3.  Alternate Hint " Is the probability of 2 females & 2 males greater than 50%?"

  Yes
  No
  Maybe
  There is not enough information to determine the answer.