$P = \dfrac{\text{number of favorable ways}}{\text{total number of ways}}$

Find the probability that somebody is healthy given that they have positive test result?

Problem
A disease is known to affect 1 in 10,000 people. A screening test for the disease shows a positive result for 99% of the people with the disease. The test also shows positive for 2% of people who do not have the disease. Find the probability that somebody is healthy given that they have positive test result?

A.   99.51% C.   46.32%
B.   12.32% D.   78.36%

 

A coin is so unbalanced that you are likely to get two heads in two successive throws as you are to get tails in one

Problem
A coin is so unbalanced that you are likely to get two heads in two successive throws as you are to get tails in one. What is the probability of getting heads in a single throw?

A.   0.168 C.   0.681
B.   0.618 D.   0.816

 

Probability That 1, 2, 3, 4 of the Recruits Will Receive the Correct Size of Boots

Situation
Four army recruits went to the supply room to get their military boots. Their shoe sizes were 7, 8, 9 & 10. The supply officer, after being informed of their sizes, prepared the four pairs of boots they need. If the boots are handed to each of the four recruits at random, what is the probability that...

  1. exactly 3 of them will receive the correct shoe size?
    A.   1/16 C.   1/12
    B.   1/24 D.   0

     

  2. all of them will receive the correct shoe size?
    A.   1/16 C.   1/12
    B.   1/24 D.   0

     

  3. none of them will receive the correct shoe size
    A.   3/8 C.   1/16
    B.   23/24 D.   5/12

 

Expected Profit for the Acceptance of Estimate of an Engineering Company

Problem
An engineering company prepares an estimate for a job. The cost of preparing the estimate is Php10,000. The amount of profit over and above the Php10,000 is Php25,000 if their estimate is accepted. The probability that their estimate will be accepted 0.7 and the probability that their estimate will not be accepted is 0.3. What is the expected profit?

A.   Php12,500 C.   Php14,500
B.   Php13,500 D.   Php10,500

 

Probability That A Randomly Selected Chord Exceeds The Length Of The Radius Of Circle

Situation
If a chord is selected at random on a fixed circle what is the probability that its length exceeds the radius of the circle?

  1. Assume that the distance of the chord from the center of the circle is uniformly distributed.
    A.   0.5 C.   0.866
    B.   0.667 D.   0.75
  2. Assume that the midpoint of the chord is evenly distributed over the circle.
    A.   0.5 C.   0.866
    B.   0.667 D.   0.75
  3. Assume that the end points of the chord are uniformly distributed over the circumference of the circle.
    A.   0.5 C.   0.866
    B.   0.667 D.   0.75