1. Helen is allocating time to studying for homework. She thinks that with the a

Question

1. Helen is allocating time to studying for homework. She thinks that with the appropriate amount of studying, she has a 70% chance of getting an A in Spanish, and a 20% chance of getting a B in Marketing. What is the probability that Helen gets an A or a B in Marketing?

2. Homework are approaching and Helen is allocating time to studying for Homeworks. She plays for the very successful women’s lacrosse team and must schedule her studying around lacrosse practices and play-off games. The entire team assumes that the probability of making the play-offs is 50%. Helen thinks that with the appropriate preparation, she has a 70% chance of getting an A in Marketing, but this chance decreases to 60% if the lacrosse team makes the play-offs. Find the probability of getting an A in Marketing and making the lacrosse play-offs.

3. Homeworks are approaching and Helen is allocating time to studying for Homeworks. She plays for the very successful women’s lacrosse team and must schedule her studying around lacrosse practices and play-off games. She thinks that with the appropriate preparation, she has a 70% chance of getting an A in Marketing. She also believes that this chance will decrease to 60% if the lacrosse team makes the play-offs. Are getting an A on the exam and being in the lacrosse play-offs independent events? Show evidence of your response.

Explanation / Answer

1. As getting A in spanish and getting B in marketing both are independent events so

probability that Helen gets an A or a B in Marketing = 0.7 + 0.2 = 0.9

2. Probability of making playoffs = 0.50

probability of getting an A in Marketing and making the lacrosse play-offs.

Pr (A in marketing and Making the play-offs) = Pr(A in marketing l making the plaoffs) * Pr( Making the playoffs)

= 0.6 * 0.5 = 0.30

3. Event X : getting an A on the marketing

Event Y : being in the lacrosse play-offs

So both event will be indendent if

P(X and Y) = P(X) P(Y)

so P(getitng an A and being in the playoffs) = 0.6 * 0.5 = 0.3

P(getting an A ) = 0.5 * 0.6 + 0.5 * 0.7 = 0.65

P( being in playoffs) = 0.5

so P(getting an A ) * P( being in playoffs) = 0.65 * 0. 5 = 0.325 0.30

so both events are not independent. If these events were to be independent there will no effect of playoffs on getting A on marketing.

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