Question

Question 1 2 pts

In a sample of 80 adults, 28 said that they would buy a car from a friend. Three adults are selected at random without replacement. Find the probability that none of the three would buy a car from a friend.

34.30%

28.80%

26.90%

21.67%

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Question 2 2 pts

A sock drawer has 17 folded pairs of socks, with 8 pairs of white, 5 pairs of black and 4 pairs of blue. What is the probability, without looking in the drawer, that you will first select and remove a black pair, then select either a blue or a white pair?

70.59%

22.06%

20.76%

29.41%

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Question 3 2 pts

An investment advisor believes that there is a 60% chance of making money by investing in a specific stock. If the stock makes money, then there is a 50% chance that among those making money, they would also get a dividend. Find the probability that the investor makes money and receive a dividend.

10%

50%

60%

30%

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Question 4 2 pts

An investment advisor believes that there is a 60% chance of making money by investing in a specific stock. If the stock makes money, then there is a 50% chance that among those making money, they would also get a dividend. Find the probability that the investor makes money and receive a dividend.

50%

60%

30%

10%

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Question 5 2 pts

A smartphone company found in a survey that 6% of people did not own a smartphone, 15% owned a smartphone only, 26% owned a smartphone and only a tablet, 32% owned a smartphone and only a computer, and 21% owned all three. If a person were selected at random, what is the probability that the person would own a smartphone only or a smartphone and computer?

42%

32%

47%

41%

Answer 1

1) P(A) = Probability that a randomly selected adult would buy a car from friend = 0.35
Probability that none of the three randomly selected adults would buy a car from friend = (1-0.35)³ = 0.27 ~ 27% Option C.

2) 17 folded pair: 8 white, 5 black, 4 blue
First we select and remove a black pair with probability: 5/17 = 0.294
Then we select either a blue or white pair, i.e. P(Blue or White)
= 1 - P(Black) = 1 - (4/16) = 0.75
So probability of occurence of both the events = 0.294 x 0.75 = 0.2206 = 22.06% Option B.

3) Event A: Chance of making money by investing in a specific stock
P(A) = 0.60
Event B: Chance of recieving dividend.
Given: If a stock makes money, chances of getting dividend is 50 %...conditional probability : P(B | A) = 0.50
We have to find the probabiility that the investor makes money and recieves a dividend i.e.P(A ∩ B)
By using conditional probability, we have: P(A ∩ B) = P(A) . P(B|A)
P(A ∩ B) = 0.60 x 0.50 = 0.30 = 30% Option D.

4) Same as 3. 30% Option C.

5) Since 15% own a smartphone only and 32 % own a smartphone and computer, probability that a random person would own a smartphone only or a smartphone and computer is 15 + 32 = 47% Option C.