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kolezko [41]
3 years ago
12

What is the area of the following circle?

Mathematics
1 answer:
Sati [7]3 years ago
4 0

Answer:

A =153.86

Step-by-step explanation:

The area of a circle is given by

A = pi r^2

We know pi = 3.14 and the radius is 7

A = 3.14 * 7^2

A =153.86

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Suppose a geyser has a mean time between irruption’s of 75 minutes. If the interval of time between the eruption is normally dis
lesya [120]

Answer:

(a) The probability that a randomly selected Time interval between irruption is longer than 84 minutes is 0.3264.

(b) The probability that a random sample of 13 time intervals between irruption has a mean longer than 84 minutes is 0.0526.

(c) The probability that a random sample of 20 time intervals between irruption has a mean longer than 84 minutes is 0.0222.

(d) The probability decreases because the variability in the sample mean decreases as we increase the sample size

(e) The population mean may be larger than 75 minutes between irruption.

Step-by-step explanation:

We are given that a geyser has a mean time between irruption of 75 minutes. Also, the interval of time between the eruption is normally distributed with a standard deviation of 20 minutes.

(a) Let X = <u><em>the interval of time between the eruption</em></u>

So, X ~ Normal(\mu=75, \sigma^{2} =20)

The z-score probability distribution for the normal distribution is given by;

                            Z  =  \frac{X-\mu}{\sigma}  ~ N(0,1)

where, \mu = population mean time between irruption = 75 minutes

           \sigma = standard deviation = 20 minutes

Now, the probability that a randomly selected Time interval between irruption is longer than 84 minutes is given by = P(X > 84 min)

 

    P(X > 84 min) = P( \frac{X-\mu}{\sigma} > \frac{84-75}{20} ) = P(Z > 0.45) = 1 - P(Z \leq 0.45)

                                                        = 1 - 0.6736 = <u>0.3264</u>

The above probability is calculated by looking at the value of x = 0.45 in the z table which has an area of 0.6736.

(b) Let \bar X = <u><em>sample time intervals between the eruption</em></u>

The z-score probability distribution for the sample mean is given by;

                            Z  =  \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }  ~ N(0,1)

where, \mu = population mean time between irruption = 75 minutes

           \sigma = standard deviation = 20 minutes

           n = sample of time intervals = 13

Now, the probability that a random sample of 13 time intervals between irruption has a mean longer than 84 minutes is given by = P(\bar X > 84 min)

 

    P(\bar X > 84 min) = P( \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } } > \frac{84-75}{\frac{20}{\sqrt{13} } } ) = P(Z > 1.62) = 1 - P(Z \leq 1.62)

                                                        = 1 - 0.9474 = <u>0.0526</u>

The above probability is calculated by looking at the value of x = 1.62 in the z table which has an area of 0.9474.

(c) Let \bar X = <u><em>sample time intervals between the eruption</em></u>

The z-score probability distribution for the sample mean is given by;

                            Z  =  \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }  ~ N(0,1)

where, \mu = population mean time between irruption = 75 minutes

           \sigma = standard deviation = 20 minutes

           n = sample of time intervals = 20

Now, the probability that a random sample of 20 time intervals between irruption has a mean longer than 84 minutes is given by = P(\bar X > 84 min)

 

    P(\bar X > 84 min) = P( \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } } > \frac{84-75}{\frac{20}{\sqrt{20} } } ) = P(Z > 2.01) = 1 - P(Z \leq 2.01)

                                                        = 1 - 0.9778 = <u>0.0222</u>

The above probability is calculated by looking at the value of x = 2.01 in the z table which has an area of 0.9778.

(d) When increasing the sample size, the probability decreases because the variability in the sample mean decreases as we increase the sample size which we can clearly see in part (b) and (c) of the question.

(e) Since it is clear that the probability that a random sample of 20 time intervals between irruption has a mean longer than 84 minutes is very slow(less than 5%0 which means that this is an unusual event. So, we can conclude that the population mean may be larger than 75 minutes between irruption.

8 0
3 years ago
I am in confusion ❤️
muminat

Answer:

The Brain

Step-by-step explanation:

It goes down 3 and moves to the right 2

so its -3/2 =- 1.5

you slope is -1.5❤✔ hope I helped!

5 0
3 years ago
PLEASE HELP!! (will give brainliest for best answer)
Likurg_2 [28]

Answer:

i think the answer should be 60 ft long bc that would leave 10ft on each side of the banner

Step-by-step explanation:

hope this helps

5 0
3 years ago
78. How can the polynomial, 18x^2 + 30x^6 be factored using the GCF?
dexar [7]

Answer:

6x^2(5x^4 +3)

Step-by-step explanation:

The greatest common factor of 18 = 3·6 and 30 = 5·6 is 6.

The greatest common factor of x^2 and x^6 is x^2.

Factoring 6x^2 from both terms, we get ...

... 18x^2 +30x^6 = 6x^2(3 +5x^4)

_____

<em>Comment on the question</em>

Since this answer is not among the answer choices, I suggest you ask your teacher to demonstrate how this problem is worked.

It appears as though the answers go with the problem 18x^9 +30x^6. Maybe there's a typo somewhere. For that problem, the best choice is the 2nd answer.

6 0
3 years ago
11-5 practice volumes of pyramids and cones
Minchanka [31]

Answer:

Step-by-step explanation:

Volume for a  cone =  1/3 * pi * r^{2} * h

Volume for a pyramid =  1/3 * area of base * h

4 0
3 years ago
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