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3 years ago

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wind turbines generate large amounts of electricity from wind energy. the blades on a wind turbine can revolve 22 times per minu

te. if a wind turbine runs for 1 hour,about how many times do the blades revolve?remember, there are 60 minutes in 1 hour.

1 answer:

lesya [120]3 years ago

5 0

Answer:

1320 times

Step-by-step explanation:

Time = 1 h × (60 min/1 h) = 60 min

Revolutions = 60 min × (22 rev/1 min) = 1320 rev

The blades revolve 1320 times per hour.

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The graph Of y= x2 + 11x + 24 is equivalent to the graph of which equation?

stepan [7]

Answer:

Step-by-step explanation:

Please use " ^ " to indicate exponentation: y= x^2 + 11x + 24. Thanks.

Because x^2 is positive, the graph of this parabola opens up.

We can find the vertex and roots (zeros) as follows, using the quadratic formula:

With a = 1, b = 11 and c = 24,

-11 ± √ [ (11^2-4(1)(24) ] -11 ± √25

x = ------------------------------------ = --------------- = -3 and x = -8

2(1) 2

This tells us that the x-intercepts are at (-3, 0) and (-8, 0). The minimum value is at x = -b / (2a), which here is x = -11 / [2] = -5 1/2 (which is halfway between the zeros).

The vertex (and thus, the minimum) is at (-5 1/2, f(-5 1/2) ).

7 0

3 years ago

If a polyhedron has 5 faces and 7 vertices, then it must have how many edges? Please show step-by-step work

Juli2301 [7.4K]

Answer:

10 edges

Step-by-step explanation:

we know that

The Euler's formula state that: In a polyhedron, the number of vertices, minus the number of edges, plus the number of faces, is equal to two

$V - E + F = 2$

in this problem we have

$V=7\\E=?\\F=5$

substitute the given values

$7 - E + 5 = 2$

solve for E

Combine like terms in the left side

$12 - E = 2$

subtract 12 both sides

$- E = -10$

Multiply by -1 both sides

$E =10$

8 0

3 years ago

4/1 = 12/3 so 12 cups =_____ quarts

riadik2000 [5.3K]

Answer:

3 quarts

Step-by-step explanation:

4/1 = 12/3 so 12 cups =3 quarts

6 0

3 years ago

Find the value of x.

melamori03 [73]

9514 1404 393

Answer:

(b) 48

Step-by-step explanation:

In this geometry, the altitude (x) is the root of the product of the segments of the hypotenuse.

x = √(36·64) = √36×√64 = 6×8

x = 48

_____

All of the triangles are similar, so the ratios of corresponding sides are the same.

short side/long side = x/64 = 36/x

x^2 = (64)(36) . . . . as above

6 0

3 years ago

To estimate the mean height μ of male students on your campus,you will measure an SRS of students. You know from government data

nexus9112 [7]

Answer:

a) $\sigma = 0.167$

b) We need a sample of at least 282 young men.

Step-by-step explanation:

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

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

This Zscore is how many standard deviations the value of the measure X 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.

(a) What standard deviation must x have so that 99.7% of allsamples give an x within one-half inch of μ?

To solve this problem, we use the 68-95-99.7 rule. This rule states that:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviations of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we want 99.7% of all samples give X within one-half inch of $\mu$ . So $X - \mu = 0.5$ must have $Z = 3$ and $X - \mu = -0.5$ must have $Z = -3$ .

So

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

$3 = \frac{0.5}{\sigma}$

$3\sigma = 0.5$

$\sigma = \frac{0.5}{3}$

$\sigma = 0.167$

(b) How large an SRS do you need to reduce the standard deviationof x to the value you found in part (a)?

You know from government data that heights of young men are approximately Normal with standard deviation about 2.8 inches. This means that $\sigma = 2.8$

The standard deviation of a sample of n young man is given by the following formula

$s = \frac{\sigma}{\sqrt{n}}$

We want to have $s = 0.167$

$0.167 = \frac{2.8}{\sqrt{n}}$

$0.167\sqrt{n} = 2.8$

$\sqrt{n} = \frac{2.8}{0.167}$

$\sqrt{n} = 16.77$

$\sqrt{n}^{2} = 16.77^{2}$

$n = 281.23$

We need a sample of at least 282 young men.

6 0

4 years ago