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3 years ago

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A cylindrical milk storage tank needs to be built to hold 84.78 cubic feet of milk. The foundation for the tank has already been

poured out of 6 foot thick concrete. The radius of the tank will be 3 feet. What is the minium height that the tank can be (in feet)?

1 answer:

Romashka [77]3 years ago

8 0

Answer:

3 or 2.999 (probably 3)

Step-by-step explanation:

So the volume of a cylinder = πr^2 * h

h = height

r = radius

now we know the radius. Leaving us with a simple equation which is:

π*9*h = 9π*h = 84.78 =

π*h = 9.42

h = 9.42 / π = 2.99847912785......

but we can round this to 2.999 or just 3. if you use 2.999 the volume is 84.79 which is as close as I'm gonna try to get. And you might ask why we're rounding to 2.999 and not 2.998? This is because that huge number is the minimum. And 2.998 is smaller than that huge number, meaning it would technically be less than 84.78 cubic ft. But this doesn't really matter because the answer your teacher is probably looking for is 3.

Reference my work if you're are confused, however, it's really messy so sorry about that.

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Use substitution to determine if the solution is correct (PINK HIGHLIGHTED ONE!!!)

mart [117]

Answer:

It is not correct.

Step-by-step explanation:

If you plug 4 in for x, you get -2*4+5=13. This simplifies to: -8+5=13. This is an untrue statement since -8+5 is actually -3, not 13.

Hope this is helpful! :)

4 0

3 years ago

Read 2 more answers

According to a Yale program on climate change communication survey, 71% of Americans think global warming is happening.† (a) For

SpyIntel [72]

Answer:

a) 0.2741 = 27.41% probability that at least 13 believe global warming is occurring

b) 0.7611 = 76.11% probability that at least 110 believe global warming is occurring

Step-by-step explanation:

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

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:

$p = 0.71$

(a) For a sample of 16 Americans, what is the probability that at least 13 believe global warming is occurring?

Here $n = 16$ , we want $P(X \geq 13)$ . So

$P(X \geq 13) = P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16)$

In which

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 13) = C_{16,13}.(0.71)^{13}.(0.29)^{3} = 0.1591$

$P(X = 14) = C_{16,14}.(0.71)^{14}.(0.29)^{2} = 0.0835$

$P(X = 15) = C_{16,15}.(0.71)^{15}.(0.29)^{1} = 0.0273$

$P(X = 16) = C_{16,16}.(0.71)^{16}.(0.29)^{0} = 0.0042$

$P(X \geq 13) = P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16) = 0.1591 + 0.0835 + 0.0273 + 0.0042 = 0.2741$

0.2741 = 27.41% probability that at least 13 believe global warming is occurring

(b) For a sample of 160 Americans, what is the probability that at least 110 believe global warming is occurring?

Now $n = 160$ . So

$\mu = E(X) = np = 160*0.71 = 113.6$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{160*0.71*0.29} = 5.74$

Using continuity correction, this is $P(X \geq 110 - 0.5) = P(X \geq 109.5)$ , which is 1 subtracted by the pvalue of Z when X = 109.5. So

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

$Z = \frac{109.5 - 113.6}{5.74}$

$Z = -0.71$

$Z = -0.71$ has a pvalue of 0.2389

1 - 0.2389 = 0.7611

0.7611 = 76.11% probability that at least 110 believe global warming is occurring

3 0

3 years ago

The ratio of two complementary angles is 17:13. What is the measure of the smaller angle?

Mariana [72]

We know by definition that complementary angles add up to 90 degrees. We can set up an equation using the ration given:

17x+13x=90, with x representing the amount you need to multiply the ratio by to get 90.

17x+13x=90
30x=90
x=3

We now know that the number we multiply the ratio by is 3. The smaller number in the ratio is 13, and so therefore we multiply it by 3.

3*13=39

The answer is 39 degrees.

8 0

3 years ago

There are 20 20 coins in a jar. Each coin is either a nickel or a quarter. If one of the coins is selected at random, the probab

sveta [45]

Answer: there are 8 quarters in the jar

Step-by-step explanation:

Let x represent the number of nickels that is inside the jar.

The total number of coins inside the jar is 20.

Probability is expressed as

Number of possible or favorable outcomes/total number of outcomes.

The probability of selecting a nickel is 0.6. This is expressed as

0.6 = x/20

Cross multiplying, it becomes

x = 20 × 0.6

x = 12

Since there are 12 nickels inside the jar, then the number of quarters would be

20 - 12 = 8

3 0

3 years ago

The sum of ruqiyo’s age and Mohammed’s age is 117. Five times ruqiyo’s age is 9 more than 3 times mohammed’s age. How old is eac

Bess [88]

Answer:

45 and 72

Step-by-step explanation:

Let the ages be r and m

<u>We have:</u>

r + m = 117
5r = 9 + 3m

<u>Substitute m in the second equation and solve for r:</u>

m = 117 - r
5r = 9 + 3( 117 - r)
5r = 9 + 351 - 3r
5r + 3r = 360
8r = 360
r = 360/8
r = 45

<u>Then m is</u>

m = 117 - 45 = 72

3 0

3 years ago