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2 years ago

Given that P(A)=0.5 and p(AUB)=0.6 find the P(B) if P(A/B) =0.4?

1 answer:

4 0

First we have to find p(AnB)
P(A/B)=p(AnB)/p(A)
P(AnB)=p(A) x p(A/B)
P(AnB)=0.5 x 0.4 = 0.2
Then to find p(B)
P(A∪B) = P(A) + P(B) - P(A∩B)

P(A∪B) = 0.5+p(B)-0.2
0.6=0.3+p(B)
P(B)=0.6-0.3=0.3

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kicyunya [14]

Answer:

8.69% probability that at least 285 rooms will be occupied.

Step-by-step explanation:

For each booked hotel room, there are only two possible outcomes. Either there is a cancelation, or there is not. So we use concepts of the binomial probability distribution to solve this question.

However, we are working with a big sample. So i am going to aproximate this binomial distribution to the normal.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

A popular resort hotel has 300 rooms and is usually fully booked. This means that $n = 300$

About 7% of the time a reservation is canceled before the 6:00 p.m. deadline with no pen-alty. What is the probability that at least 285 rooms will be occupied?

Here a success is a reservation not being canceled. There is a 7% probability that a reservation is canceled, and a 100 - 7 = 93% probability that a reservation is not canceled, that is, a room is occupied. So we use $p = 0.93$

Approximating the binomial to the normal.

$E(X) = np = 300*0.93 = 279$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{300*0.93*0.07} = 4.42$

The probability that at least 285 rooms will be occupied is 1 subtracted by the pvalue of Z when X = 285. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{285- 279}{4.42}$

$Z = 1.36$

$Z = 1.36$ has a pvalue of 0.9131.

So there is a 1-0.9131 = 0.0869 = 8.69% probability that at least 285 rooms will be occupied.

8 0

2 years ago

Cheryl is now x years old. Her cousin is ⅓ Cheryl’s age. Find her cousin’s age in terms of x.

nikklg [1K]

x/3= her cousins age

4 0

3 years ago

Jen has 6 yards of fabric and wants to make a new dress and shorts she used 3 1/3 yards of the fabric on her new dress how much

kodGreya [7K]

Answer:

$2\frac{2}{3}\ yards$

Step-by-step explanation:

we know that

To find out how much fabric Jen has left for the shorts, subtract the yards of fabric used in her new dress from the total yards of fabric Jen has.

$6-3\frac{1}{3}$

Convert mixed number to an improper fraction

$3\frac{1}{3}=\frac{3*3+1}{3}=\frac{10}{3}$

substitute

$6-3\frac{1}{3}=6-\frac{10}{3}=\frac{8}{3}\ yards$

Convert to mixed number

$\frac{8}{3}\ yards=\frac{6}{3}+\frac{2}{3}=2\frac{2}{3}\ yards$

5 0

3 years ago

Find the percent of tip:

r-ruslan [8.4K]

The answer is 14%

Cost of meal is 100%: $18.50 is 100%
Tip is x%: $2.59 is x

Make a proportion:
$18.50 : 100% = $2.59 : x
x = 100% * $2.59 : $18.50
x = 14%

4 0

2 years ago

What is the image point of (-1,9) after a translation left 1 unit and down 1 unit

notka56 [123]

Answer

(-2,8)

Step-by-step explanation:

4 0

3 years ago