In: Math
In Hawaii, January is a favorite month for surfing since 60% of the days have a surf of at least 6 feet.† You work day shifts in a Honolulu hospital emergency room. At the beginning of each month you select your days off, and you pick 7 days at random in January to go surfing. Let r be the number of days the surf is at least 6 feet.
(a) Make a histogram of the probability distribution of r.
(b) What is the probability of getting 4 or more days when the
surf is at least 6 feet? (Round your answer to three decimal
places.)
(c) What is the probability of getting fewer than 2 days when the
surf is at least 6 feet? (Round your answer to three decimal
places.)
(d) What is the expected number of days when the surf will be at
least 6 feet? (Round your answer to two decimal places.)
days
(e) What is the standard deviation of the r-probability
distribution? (Round your answer to three decimal places.)
days
(f) Can you be fairly confident that the surf will be at least 6
feet high on one of your days off? Explain. (Round your answer to
three decimal places.)
---Select--- Yes No , because the probability of at least 1 day with surf of at least 6 feet is and the expected number of days when the surf will be at least 6 feet is ---Select--- less than equal to greater than one.
In Hawaii, January is a favorite month for surfing since 60% of the days have a surf of at least 6 feet. This is same as
the probability that any given day in January has a surf of at least 6 feet is 0.60
you pick 7 days at random in January to go surfing. Let R be the number of days the surf is at least 6 feet. We can say that R has a Binomial distribution with parameters, number of trials (number of days gone on surfing) n=7 and success probability (the probability that any given day in January has a surf of at least 6 feet) p=0.60
The probability that R=r days when the surf is at least 6 feet is
We can get the value of P(R=r) for r=0,1,...,7 as below
We can get the following table of probabilities
r | P(R=r) |
0 | 0.0016 |
1 | 0.0172 |
2 | 0.0774 |
3 | 0.1935 |
4 | 0.2903 |
5 | 0.2613 |
6 | 0.1306 |
7 | 0.0280 |
(a) Make a histogram of the probability distribution of r.
We create a bar chart using the table
(b) What is the probability of getting 4 or more days when the
surf is at least 6 feet? (Round your answer to three decimal
places.)
ans: the probability of getting 4 or more days when the surf is
at least 6 feet is 0.710
(c) What is the probability of getting fewer than 2 days when the
surf is at least 6 feet? (Round your answer to three decimal
places.)
ans: the probability of getting fewer than 2 days when the surf
is at least 6 feet is 0.019
(d) What is the expected number of days when the surf will be at
least 6 feet? (Round your answer to two decimal places.)
days
The expected value of R using the formula for Binomial expectation is
ans: the expected number of days when the surf will be at least
6 feet is 4.20 days
(e) What is the standard deviation of the r-probability
distribution? (Round your answer to three decimal places.)
days
The standard deviation of R using the formula for Binomial
distribution
ans: the standard deviation of the r-probability distribution is 1.296 days
(f) Can you be fairly confident that the surf will be at least 6
feet high on one of your days off? Explain. (Round your answer to
three decimal places.)
the probability of at least 1 day with surf of at least 6 feet is
ans: Yes , because the probability of at least 1 day with surf of at least 6 feet is 0.998 and the expected number of days when the surf will be at least 6 feet is greater than one.