Simplify the expression. Write your answer as a power.

For a certain river, suppose the drought length Y is the number of consecutive time intervals in which the water supply remains

AnnZ [28]

Answer:

a) There is a 9% probability that a drought lasts exactly 3 intervals.

There is an 85.5% probability that a drought lasts at most 3 intervals.

b)There is a 14.5% probability that the length of a drought exceeds its mean value by at least one standard deviation

Step-by-step explanation:

The geometric distribution is the number of failures expected before you get a success in a series of Bernoulli trials.

It has the following probability density formula:

$f(x) = (1-p)^{x}p$

In which p is the probability of a success.

The mean of the geometric distribution is given by the following formula:

$\mu = \frac{1-p}{p}$

The standard deviation of the geometric distribution is given by the following formula:

$\sigma = \sqrt{\frac{1-p}{p^{2}}$

In this problem, we have that:

$p = 0.383$

So

$\mu = \frac{1-p}{p} = \frac{1-0.383}{0.383} = 1.61$

$\sigma = \sqrt{\frac{1-p}{p^{2}}} = \sqrt{\frac{1-0.383}{(0.383)^{2}}} = 2.05$

(a) What is the probability that a drought lasts exactly 3 intervals?

This is $f(3)$

$f(x) = (1-p)^{x}p$

$f(3) = (1-0.383)^{3}*(0.383)$

$f(3) = 0.09$

There is a 9% probability that a drought lasts exactly 3 intervals.

At most 3 intervals?

This is $P = f(0) + f(1) + f(2) + f(3)$

$f(x) = (1-p)^{x}p$

$f(0) = (1-0.383)^{0}*(0.383) = 0.383$

$f(1) = (1-0.383)^{1}*(0.383) = 0.236$

$f(2) = (1-0.383)^{2}*(0.383) = 0.146$

Previously in this exercise, we found that $f(3) = 0.09$

So

$P = f(0) + f(1) + f(2) + f(3) = 0.383 + 0.236 + 0.146 + 0.09 = 0.855$

There is an 85.5% probability that a drought lasts at most 3 intervals.

(b) What is the probability that the length of a drought exceeds its mean value by at least one standard deviation?

This is $P(X \geq \mu+\sigma) = P(X \geq 1.61 + 2.05) = P(X \geq 3.66) = P(X \geq 4)$ .

We are working with discrete data, so 3.66 is rounded up to 4.

Either a drought lasts at least four months, or it lasts at most thee. In a), we found that the probability that it lasts at most 3 months is 0.855. The sum of these probabilities is decimal 1. So:

$P(X \leq 3) + P(X \geq 4) = 1$

$0.855 + P(X \geq 4) = 1$

$P(X \geq 4) = 0.145$

There is a 14.5% probability that the length of a drought exceeds its mean value by at least one standard deviation

8 0

3 years ago

When you use word processor functions such as spell check and thesaurus to write a second draft you are

nirvana33 [79]

C. Revising because it should be your last stage in the writing process before you publish

3 0

2 years ago

Read 2 more answers

15. Work out the<br> area of a<br> rectangle with<br> sides 3.4cm and<br> 4.5cm

pav-90 [236]

Area is length times width so

A = 4.5*3.4 which is 15.3.

The area of the rectangle is 15.3 cm

3 0

2 years ago

Read 2 more answers

Carl. put $1.10 in his piggy bank every day in the month of July. His total savings was $55 at the end of June. hat is the best

Crank

Carl would have around $90 at the end of July

8 0

3 years ago

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I’m having a lot of trouble, can someone guide me, step by step?

shutvik [7]

Answer:

Hi hopefully this helps you!

Step-by-step explanation:

To find the area of a circle you can use the formula A = πr^2

The radius of a circle is just the diameter divided by 2. In this case we know the diameter is 3, so the radius is 1.5

A = π(1.5)^2

= 7.07

Because this is a semicircle, divide this area by 2

= 3.53429 in^2

Add up the area of this semi circle with the area of the rectangle

A = (3.53429) + (3x4)

= 15.53429 in^2

To find the circumference/ perimeter of a circle use this formula C = 2πR

C = 2π(1.5)

= 9.42478 inches

Again because this is a semicircle, divide by 2

= 9.42478 / 2

= 4.71239 inches

To find the perimeter of this entire shape add up the circumference of the semicircle and the rectangle's sides and bottom

P = 4.71239 + 4 + 4 + 3

= 15.71239 inches

So the final answer would be

A = 15.53 squared inches

P = 15.71 inches

Hope this helps! Best of luck in your studies <3

6 0

2 years ago