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3 years ago

Which proportion can be used to find 65% of 90?

Mathematics

1 answer:

ra1l [238]3 years ago

3 0

X 65%
———— = ———-
90 100

1) multiply across
90 • 65 = 5,850

2) divide what’s left over.
5,850 / 100 = 58.5

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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:

$p = 0.383$

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

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

(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 $f(3) = 0.09$

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

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

Calculating area of rectangle with a diagonal of 5m height of 3m and length of 4m

bagirrra123 [75]

Answer:

area = 12 m²

Step-by-step explanation:

area = L x W

area = 4 x 3 = 12 m²

8 0

2 years ago

Read 2 more answers

Jerald jumped from a bungee tower. If the equation that models his height, in feet, is h = –16t2 + 729, where t is the time in s

Snezhnost [94]

Answer. First option: t > 6.25

Solution:

Height (in feet): h=-16t^2+729

For which interval of time is h less than 104 feet above the ground?

h < 104

Replacing h for -16t^2+729

-16t^2+729 < 104

Solving for h: Subtracting 729 both sides of the inequality:

-16t^2+729-729 < 104-729

-16t^2 < -625

Multiplying the inequality by -1:

(-1)(-16t^2 < -625)

16t^2 > 625

Dividing both sides of the inequality by 16:

16t^2/16 > 625/16

t^2 > 39.0625

Replacing t^2 by [ Absolute value (t) ]^2:

[ Absolute value (t) ]^2 > 39.0625

Square root both sides of the inequality:

sqrt { [ Absolute value (t) ]^2 } > sqrt (39.0625)

Absolute value (t) > 6.25

t < -6.25 or t > 6.25, but t can not be negative, then the solution is:

t > 6.25

5 0

3 years ago

Read 2 more answers

Can someone answer plz

NeX [460]

1.D 2. A 3.C 4.D

1 Is the monomial as it only contains one expression.

2. Is the difference of squares because something squared minus something squared.

3. Is standard because it is of the form

$a_nx^n+ a_{n-1}x^{n-1}+...+a_1x+a_0$

4. We know D is the not the monomial simply because its power is negative which means it does not fit the definition of a polynomial.

3 0

2 years ago

Find the 72nd term of the arithmetic sequence -27, -11, 5, ...

MAXImum [283]

Step-by-step explanation:

first identify the common difference

The first term which i will define by u⁰=-27

u¹=u⁰+(1)d where d is the common difference and u¹ is the second term

u¹=-27+d

-11=-27+d

d=27-11=16

The 72nd term would be u⁷¹ since we started from u⁰ as our first term:

Use the explicit relation given by:

u(n)=u⁰+(n)d

u(71)=-27+71(d)

u⁷¹=-27+71(16)

u⁷¹=-27+1136

u⁷¹=1109

8 0

2 years ago