Basic Statistics Week 3 Quiz Answer Probability
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Statistics Week 3 Quiz Answer | Probability with you..
Probability
Question 1)
Your friend told you about someone really smart who made a good deal
with the bank regarding his/her mortgage and who knows everything about
the financial crisis that started in 2008. Which of the following
statements is more likely?
I. Your friend talked about a man.
II. Your friend talked about a man with a job in the banking
world.
- Both statements are equally likely.
- Statement I is more likely.
- Statement II is more likely
Question 2)
You roll a dice five times. The outcomes are: 6 6 6 6 6. Then you
repeat this and you find: 1 4 3 5 2.
Which of the following outcomes is most likely?
- The first outcome is more likely.
- The second outcome is more likely.
- Both outcomes are equally likely
Question 3)
Imagine you're at the beach. You're really thirsty and decide to go to
a beach stand to get some coke. When you arrive you see there's a queue
consisting of two girls and one boy. Unfortunately the stand has only
one coke left. You've learned that three in ten girls drink coke and 60
percent of boys drink coke.
How likely is it that you will get the coke?
- 0.054
- 0.196
- 0.946
- 0.804
Question 4)
You ask a couple of people at the beach what they think about the
seagulls. You propose them the statement: Seagulls are annoying. Their
responses are as follows:
13% agree
12% neutral
50% disagree
5% strongly disagree
20% strongly agree
12% neutral
50% disagree
5% strongly disagree
20% strongly agree
What is the chance of a random person responding with 'agree' given
that he/she is not neutral?
- 0.13
- 0.25
- 0.15
- 0.52
Question 5)
Imagine you ask some students which subject they prefer: statistics or
English. There are a lot of people that love statistics (B) and a lot of
people that love English (C). However, there are also people that can't
make a decision and tell you that they like both the subjects (D). When
you look further into the results you realise that all the female
students had a positive opinion about statistics (A).
Which of these events (A, B, C, D) are disjoint?
- A and C & A and D
- B and C & C and D
- A and C & B and C
- A and D & B and C
Question 6)
You collect four shells from the beach. You know that there are only
three types of shells on the beach, and these shells occur in equal
amounts. How many different events are possible?
- 4
- 81
- 3
- 12
Question 7)
Twenty people take a statistics exam. Jonas scored five out of ten and
Emma scored eight out of ten. Every score (1 to 10) is equally likely.
What is the chance of a random person out of the people that took the
exam scoring higher than Jonas, but lower than Emma?
- 0.22
- 0.4
- 0.8
- 0.2
Question 8)
How can we define probability or chance?
- as a long-run relative frequency
- as the average or expeted value of a random variable
- as a probable value that a random variable will take
- as the relative uncertainty about events
Question 9)
You are rushing out to get to your appointment in 30 minutes. From
experience you know that most of the time you travel this distance in 30
minutes. However, half of the time there is heavy traffic. In the past,
there has been heavy traffic and you have made it to your appointment
within 30 minutes 34% of the time.
You get out on the street and see that there is heavy traffic. What is
the chance you will get to your appointment on time?
- 0.17
- 0.34
- 0.5
- 0.68
Question 10)
What is the probability of event A given event B?
- 0.16
- 0.42
- 1.03
- 0.73
Question 11)
You have a pot with 100 balls. 20 of them are red, 50 are blue and 30
are green. You decide to draw 5 balls from the pot without replacement
(i.e. you don't put a ball back in the pot once it has been taken out).
What is the probability of drawing five blue balls?
Give your answer to 3 decimal places.
choose(100, 5)
choose(50, 5)
choose(50, 5) / choose(100, 5)
# [1] 0.02814225
Question 12)
On a single train journey there is a probability of 0.4 that your
ticket will be checked. You make a return-journey, what is the
probability that your ticket will be checked only once?
Give your answer as a proportion, rounding to two decimal places.
Answer:
0.4 * 0.6 + 0.6 * 0.4
# [1] 0.48
Question 13)
You roll a pair of dice 20 times and record how often you get a total
of 5 or 10. What is your best guess for the relative frequency that this
event (a total of 5 or 10) occurs without seeing the actual data?
Give your answer as a proportion, rounding to three decimal places.
Enter answer here
Question 14)
The chance that the front light on your bike will fail is 0.2, the
chance that your rear light will fail is 0.1 and the chance that both
will fail is 0.04. What is the chance that both lights will work?
(regardless of the answer you should do something about this situation
of course).
Give your answer as a proportion, rounding to two decimal places.
Answer:
7 / 36
# [1] 0.1944444
Question 15)
Which of the following statements are correct?
I. A discrete random variable can take a finite number of distinct
values.
II. Height is an example of a continuous random variable.
- Both statements are correct.
- Statement I is correct, statement II is incorrect.
- Statement I is incorrect, statement II is correct.
- Both statements are incorrect.
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