# Sols3.pdf - ECOM90009 Quantitative Methods for Business...

This preview shows pages 1–3. Sign up to view the full content.

ECOM90009 - Quantitative Methods for Business Se cond Se mester, 201 7 Workshop 3: Probability and Discrete Distributions Solutions to Preparation Questions 1. (a) If we assume that the probability is independent of whether a family already has a boy or a girl, then the probability that the family’s other child is a girl is 1/2 or 50%. (b) Probability = 2/3. There are three ways in which the family could have at least one boy (BB, BG, GB), and only two of these involve having a girl. Each of these outcomes is equally likely. (c) The two probabilities are different because they describe different experiments. In (a) the experiment is the process of a family having a second child, and we assumed that the gender of each child is an independent event (a reasonable assumption), whereas in (b) the experiment is you observing a family, con- ditional on an event, and the events are not (cannot be) independent in this case. 2. Recall that two events are independent if knowing that one has occurred gives us no new information about the likelihood of the other occurring. 3. (a) Let A be the event in which a randomly selected person is a teenager, and let B be the event in which a randomly selected person is a casual employee. If A and B are independent, P ( A B ) = P ( A | B ) P ( B ) = P ( A ) P ( B ) 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
P ( A ) P ( B ) = 0 . 2 × 0 . 1 = 0 . 02 (b) A person’s age and employment type are not likely to be independent, because teenagers generally ﬁnd it harder to obtain a permanent job given their (relative to adults) limited skills and limited work experience.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern