Math Is Fun Forum

Mich

Guest

Probability

Hi, need help and guidance on below. appreciate your reply with thanks

Q2
a) it is noted that 8% of K students are left handed. If 20 (twenty) students are randomly selected, calculated the
i. probability that none of them are left-handed,
ii. probability that at most 2 are left-handed,
iii. standard deviation for the number of left-handed students
(b) if 50 (fifty) classes of 20 (twenty) students are randomly selected, what is the probability that 10 (ten) classes have no left-handed students?

Q3
a) Superior Contruction Pte Ltd is a successful company dealing with many major projects in Sngapore.
Recently, it has submitted its bidding for two major Goverment projects. Project A worth about $120 million and the company believes it has 40% chance of securing the project. Project B worth $1.8 billion and there is 30% chance the company can win the project. Both projects are independent of each other. What is the probability that the company:
i. will secure project A or B but not both
ii. will not secure Project A or will not secure Project B
b) Do you agree that `if two events are mutually exclusive then these two events will be independent
`? Why?
c) Provide one business-related example each, with explanation, for mutually exclusive and independent events.

zetafunc

Moderator

Registered: 2014-05-21

Posts: 2,432

Website

Re: Probability

Hi Mich,

Welcome to the forum! Have you considered registering an account here?

For Q2)(a)(i) and (ii), suppose that

is the random variable representing the number of K students who are left-handed. That is,

is binomially distributed as

The first question therefore wants you to compute

Do you know how to do this?

For part (iii), do you know how to compute the variance

from the parameters you have been given?

For part (b), you can also use a binomial distribution here, but it won't be the same as the one for part (a). Try coming up with another binomially distributed random variable

where

are parameters you should try to determine. (Hint: You can use one of your previous answers here.)

For Q3)(a), I would advise drawing a Venn diagram. For (b), what does it mean for two events

to be independent?