A student is taking a multiple-choice exam in which each question has two choices. Assuming that she has no knowledge of the co
rrect answers to any of the questions, she has decided on a strategy in which she will place two balls (marked Upper A and Upper B) into a box. She randomly selects one ball for each question and replaces the ball in the box. The marking on the ball will determine her answer to the question. There are four multiple-choice questions on the exam. Complete parts (a) through (d) below. a. What is the probability that she will get four questions correct? nothing (Round to four decimal places as needed.)
So if in the box there are 2 balls and she chose one at random, then she had a 0.5 probability of chose each ball, and then she has a 0.5 probability of choosing the ball that is associated to the correct answer, then she has a 0.5 of getting each answer correct.
Now she has 4 questions, then the probability for getting all of them correct is the product of the probabilities for each one; this is:
0.5*0.5*0.5*0.5 = 0.0625
multiplied by 100%, we get a 6.25% of getting the four answers correct using this method.
For this case, the first thing we must do is define variables. We have then: x: number of blue beads y: number of red beads We now write the inequations system: Answer: a system of linear inequations that represents the situation is:
