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Tamiku [17]
3 years ago
6

A toy falls from a window 70 feet above the ground. How long does it take the toy to hit the​ ground?

Mathematics
1 answer:
Korolek [52]3 years ago
6 0

Answer:

2.09 seconds.

Step-by-step explanation:

We are given...

y = 70 feet

v0 = 0 feet/second

a = 32 feet/second^2

We need to find t using the following equation...

y = v0 * t + (1/2) * a * t^2

70 = 0 * t + (1/2) * 32 * t^2

70 = (1/2) * 32 * t^2

70 = 16t^2

16t^2 = 70

t^2 = 4.375

t = sqrt(4.375)

t = 2.091650066

So, it will take the toy about 2.09 seconds to hit the ground.

Hope this helps!

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Read 2 more answers
A researcher reports survey results by stating that the standard error of the mean is 25 the population standard deviation is 40
bezimeni [28]

Answer:

a) A sample of 256 was used in this survey.

b) 45.14% probability that the point estimate was within ±15 of the population mean

Step-by-step explanation:

This question is solved using the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use 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.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean \mu and standard deviation \sigma, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

a. How large was the sample used in this survey?

We have that s = 25, \sigma = 400. We want to find n, so:

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

25 = \frac{400}{\sqrt{n}}

25\sqrt{n} = 400

\sqrt{n} = \frac{400}{25}

\sqrt{n} = 16

(\sqrt{n})^2 = 16^2[tex][tex]n = 256

A sample of 256 was used in this survey.

b. What is the probability that the point estimate was within ±15 of the population mean?

15 is the bounds with want, 25 is the standard error. So

Z = 15/25 = 0.6 has a pvalue of 0.7257

Z = -15/25 = -0.6 has a pvalue of 0.2743

0.7257 - 0.2743 = 0.4514

45.14% probability that the point estimate was within ±15 of the population mean

3 0
3 years ago
The wavelength of green lights is about 0.00000051 meter. What is the estimated wavelength as a single digit times a power of 10
kari74 [83]

<em><u>Answer:</u></em>

<h2>5.1 X 10^-7</h2>

<u><em>Reason:</em></u>

It is to the -7 because you would have to move the decimal left (-) 7 times to get the original 0.00000051.

Hope this helps! ;)

6 0
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