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3 years ago

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Two mountain bikers take off from the same place at the same time. One travels north at 4 mph, and the other travels east at 3 m

ph. How far apart are they after 4 hours?
A. 14 miles
B. 20 miles
C. 28 miles
D. 5 miles

1 answer:

Dafna1 [17]3 years ago

8 0

Answer:

20 miles (Answer B)

Step-by-step explanation:

The northbound biker travels (4 mph)(4 hr) = 16 mi, and

the eastbound biker travels (3 mph)(4 hr) = 12 mi.

They travel at right angles to one another. Thus, the Pythagorean Theorem applies here. The distance between the two bikers is d = √( [12 mi]^2 + [16 mi]^2 ), or √(144 + 256) mi, or √400 mi, which works out to 20 miles.

Answer B is correct.

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Step-by-step explanation:

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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:

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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.

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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 $Z = -3$ .

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

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

$0.167\sqrt{n} = 2.8$

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

$\sqrt{n} = 16.77$

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

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Answer:

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Step-by-step explanation:

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