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3 years ago

The radius of a circular track is 0.2 mile. Ellie ran around 3 times. How many kilometers did she run

1 answer:

6 0

Circumference = 2πr
So the circumference of the track is C = 2π .2 or .4π
3 times around the track is .4π x 3 or 1.2π - this is the answer but most teachers will want you to use 3.14 for pi.
so 1.2 x 3.14 = 3.768 km

Do you notice that I waited until the end to use the actual value of pi (3.14) in my calculations.
Keeping things in pi units until the very end saves time.

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Solve the equation by completing the square. Round to the nearest hundredth if necessary. x2 + 2x = 17

yawa3891 [41]

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Equation Given
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x² + 2x = 17

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Add the constant to make it perfect square
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x² + 2x + (2/2)² - ²(2/2)² = 17

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Evaluate the brackets
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x² + 2x + (1)² - ²(1)² = 17

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Form the perfect square
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(x + 1)² - 1 = 17

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Add 1 to both sides
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(x + 1)² = 17 + 1
(x + 1)² = 18

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Square root both sides
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√(x + 1)² = $\pm$ √18

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Solve for x
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x = 4.24 - 1 or - 4.24 -1

x = 3.24 or - 5.24 (nearest hundredth)

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Answer: x = x = 3.24 or - 5.24
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3 years ago

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Answer: 5,508 m3

Step-by-step explanation: V= 18 x 17 x 18 = 5,508 m3

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3 years ago

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antiseptic1488 [7]

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Life Expectancies In a study of the life expectancy of people in a certain geographic region, the mean age at death was years an

Sphinxa [80]

Answer:

The probability that the mean life expectancy of the sample is less than X years is the p-value of $Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$ , in which $\mu$ is the mean life expectancy, $\sigma$ is the standard deviation and n is the size of the sample.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes 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.

We have:

Mean $\mu$ , standard deviation $\sigma$ .

Sample of size n:

This means that the z-score is now, by the Central Limit Theorem:

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

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3 years ago

Jose can read 7 pages of his book in 5 minutes at this rate how long will it take for him to read the full 175 page book

Agata [3.3K]

Answer:

125 minutes

Step-by-step explanation:

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