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Dennis_Churaev [7]
3 years ago
9

Will u help me?

Mathematics
1 answer:
sergey [27]3 years ago
3 0

Answer:

Charles practiced for the relay race for D. 9 hours last week.

Step-by-step explanation:

First, I would find the ratios the ratios for converting hurdle to javelin and javelin to relay.

Hurdle : Javelin ; 5 : 1.5

Javelin : Relay ; 2.5 : 5 or  1 : 2

Next, find the factors compared to the original numbers for hurdle to javelin.

15 / 5 = 3

To find the amount of javelin time they did, multiply 1.5 by the factor we got, 3.

1.5 * 3 = 4.5

Finally, double 4.5, since Charles does twice as much relay than he does javelin.

4.5 * 2 = 9 hours

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Of the total population of American households, including older Americans and perhaps some not so old, 17.3% receive retirement
Alex Ar [27]

Answer:

47.54% probability that more than 20 households but fewer than 35 households receive a retirement income

Step-by-step explanation:

We use the binomial aproxiation to the normal to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

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 = 0.173, n = 120. So

\mu = E(X) = np = 120*0.173 = 20.76

\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{120*0.173*0.827} = 4.14

In a random sample of 120 households, what is the probability that more than 20 households but fewer than 35 households receive a retirement income?

We are working with discrete values, so this is the pvalue of Z when X = 35-1 = 34 subtracted by the pvalue of Z when X = 20 + 1 = 21.

X = 34

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

Z = \frac{34 - 20.76}{4.14}

Z = 3.2

Z = 3.2 has a pvalue of 0.9993

X = 21

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

Z = \frac{21 - 20.76}{4.14}

Z = 0.06

Z = 0.06 has a pvalue of 0.5239

0.9993 - 0.5239 = 0.4754

47.54% probability that more than 20 households but fewer than 35 households receive a retirement income

6 0
3 years ago
Write the inequality for the graph above.
serg [7]
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5 0
3 years ago
7(x+2)=2x-1 solve for the variable
Len [333]

Answer:

x = - 3

Step-by-step explanation:

Given

7(x + 2) = 2x - 1 ← distribute parenthesis on left side

7x + 14 = 2x - 1 ( subtract 2x from both sides )

5x + 14 = - 1 ( subtract 14 from both sides )

5x = - 15 ( divide both sides by 5 )

x = - 3

7 0
3 years ago
2/3 × n= -22 what is n?
tekilochka [14]

n would equal <em>-33</em>.

<em>n=-33</em>

6 0
3 years ago
Read 2 more answers
A person breathes 2.5 x 10^-4 in about cubic meters of air per second. How long does it take to breathe in 2.5 cubic meters of a
Ipatiy [6.2K]

Answer:

10⁴ seconds

Step-by-step explanation:

Given that,

A person breathes 2.5\times 10^{-4} in about cubic meters of air per second.

We need to find time taken to breathe 2.5 cubic meters of air.

In 1 sec = 2.5\times 10^{-4} m³ of air breathe

Let in x seconds, 2.5 m³ of air taken by the person.

x=\dfrac{2.5}{2.5\times 10^{-4}}\\\\x=10^4\ s

Hence, in 10⁴ seconds 2.5 m³ of air is taken by the person.

5 0
3 years ago
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