JinjaNinja1
New member
- Joined
- Oct 29, 2016
- Messages
- 2
Hi everyone,
I just finished taking an online test and found out that some of my answers were wrong. The questions and answers can be found in attached screenshots.
Question 1 Suppose T and Z are random variables.
a. If P(T > 2.39) = 0.07 and P(T < -2.39) = 0.07, obtain P(-2.39 < T < 2.39).
b. If P(-1.48 < Z < 1.48) = 0.86 and also P(Z > 1.48) = P(Z < -1.48), find P(Z > 1.48).
My answers to Q1:
a. P(-2.39 < T < 2.39) = -0.07
b. P(Z > 1.48) = P(Z < -1.48)
https://s9.postimg.org/7krqdwirz/image.png
I got no credit looks like it is completely wrong.
Question 2 A game of chance is played on a wheel that contains 36 numbers; 17 are red, 17 are black, and 2 are green. When the wheel is spun, the ball is equally likely to land on any of the 36 numbers. Suppose that you bet $6 on black. If the ball lands on a black number, you win $6; otherwise, you lose your $6. Let X be the amount that you win on your $6 bet. Then X is the random variable whose probability distribution is as follows:
Use this to complete parts (a) through (d).
(a) Find the expected value of the random variable X. -0.336
(b) On average, how much will you lose per play? $0.336
(c) Approximately how much would you expect to lose if you bet $6 on black 100 times? -$316.80
1000 times? -$3168.00
(d) Is the game profitable to play? Explain. (Choose the correct answer below.)
* No, because the expected value X represents the expected profit for this game. A negative number means the game is not profitable.
* Yes, because the average profit per game is positive.
* Yes, the game is profitable because you can make a profit playing the game. Each time you play, you can win $6.
* No, the game is not profitable if you can lose money by playing it. Each time you play, you can lose $6.
I got partial credit: 2/5 not sure where I went wrong.
https://s22.postimg.org/i9k9qtanl/image.png
And finally Question 3 According to an article, 39% of adults have experienced a breakup at least once during the last 10 years. Of 9 randomly selected adults, find the probability that the number, X, who have experienced a breakup at least once during the last 10 years is:
(a) exactly five: 0.1574
at most five: 1.0166
at least five: 0.1408
(b) at least one: 0.8158
at most one: 0.1842
(c) between four and six, inclusive: 1.0745
(d) Determine the probability distribution of the random variable X.
Again partial credit. 9/16
https://s11.postimg.org/b17cqcpyr/image.png
Can you please point out where they went wrong and how to correct the mistakes? I don't have a single clue on how to do the first question.
Please help!
Thanks in advance
I just finished taking an online test and found out that some of my answers were wrong. The questions and answers can be found in attached screenshots.
Question 1 Suppose T and Z are random variables.
a. If P(T > 2.39) = 0.07 and P(T < -2.39) = 0.07, obtain P(-2.39 < T < 2.39).
b. If P(-1.48 < Z < 1.48) = 0.86 and also P(Z > 1.48) = P(Z < -1.48), find P(Z > 1.48).
My answers to Q1:
a. P(-2.39 < T < 2.39) = -0.07
b. P(Z > 1.48) = P(Z < -1.48)
https://s9.postimg.org/7krqdwirz/image.png
I got no credit looks like it is completely wrong.
Question 2 A game of chance is played on a wheel that contains 36 numbers; 17 are red, 17 are black, and 2 are green. When the wheel is spun, the ball is equally likely to land on any of the 36 numbers. Suppose that you bet $6 on black. If the ball lands on a black number, you win $6; otherwise, you lose your $6. Let X be the amount that you win on your $6 bet. Then X is the random variable whose probability distribution is as follows:
x | 6 | -6 |
P(X = x) | 0.472 | 0.528 |
Use this to complete parts (a) through (d).
(a) Find the expected value of the random variable X. -0.336
(b) On average, how much will you lose per play? $0.336
(c) Approximately how much would you expect to lose if you bet $6 on black 100 times? -$316.80
1000 times? -$3168.00
(d) Is the game profitable to play? Explain. (Choose the correct answer below.)
* No, because the expected value X represents the expected profit for this game. A negative number means the game is not profitable.
* Yes, because the average profit per game is positive.
* Yes, the game is profitable because you can make a profit playing the game. Each time you play, you can win $6.
* No, the game is not profitable if you can lose money by playing it. Each time you play, you can lose $6.
I got partial credit: 2/5 not sure where I went wrong.
https://s22.postimg.org/i9k9qtanl/image.png
And finally Question 3 According to an article, 39% of adults have experienced a breakup at least once during the last 10 years. Of 9 randomly selected adults, find the probability that the number, X, who have experienced a breakup at least once during the last 10 years is:
(a) exactly five: 0.1574
at most five: 1.0166
at least five: 0.1408
(b) at least one: 0.8158
at most one: 0.1842
(c) between four and six, inclusive: 1.0745
(d) Determine the probability distribution of the random variable X.
x | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
P(X = x) | 0.1169 | 0.0673 | 0.1721 | 0.2567 | 0.2462 | 0.1574 | 0.6709 | 0.0184 | 0.0029 | 0.002 |
Again partial credit. 9/16
https://s11.postimg.org/b17cqcpyr/image.png
Can you please point out where they went wrong and how to correct the mistakes? I don't have a single clue on how to do the first question.
Please help!
Thanks in advance
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