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3 years ago

A circular running track is 1/4 of a mile long Elena runs this track completing each lap in 1/20 of an hour what is her speed

Mathematics

1 answer:

PSYCHO15rus [73]3 years ago

3 0

Answer:

The speed is equal to $5\frac{mi}{h}$

Step-by-step explanation:

we know that

The speed is equal to divide the distance by the time

Let

x------> the distance in miles

y-----> the time in hours

s----> the speed in mph

$s=\frac{x}{y}$

In this problem we have

$x=(1/4)\ mi$

$y=(1/20)\ h$

substitute

$s=\frac{(1/4)}{(1/20)}=20/4=5\frac{mi}{h}$

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Answer:

Step-by-step explanation:

30 - 11 = 19

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3 years ago

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Step-by-step explanation:

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3 years ago

A sample of 5 buttons is randomly selected and the following diameters are measured in inches. Give a point estimate for the pop

Helen [10]

Answer:

$s^2 = \frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}$

But we need to calculate the mean with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_I}{n}$

And replacing we got:

$\bar X = \frac{ 1.04+1.00+1.13+1.08+1.11}{5}= 1.072$

And for the sample variance we have:

$s^2 = \frac{(1.04-1.072)^2 +(1.00-1.072)^2 +(1.13-1.072)^2 +(1.08-1.072)^2 +(1.11-1.072)^2}{5-1}= 0.00277\ approx 0.003$

And thi is the best estimator for the population variance since is an unbiased estimator od the population variance $\sigma^2$

$E(s^2) = \sigma^2$

Step-by-step explanation:

For this case we have the following data:

1.04,1.00,1.13,1.08,1.11

And in order to estimate the population variance we can use the sample variance formula:

$s^2 = \frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}$

But we need to calculate the mean with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_I}{n}$

And replacing we got:

$\bar X = \frac{ 1.04+1.00+1.13+1.08+1.11}{5}= 1.072$

And for the sample variance we have:

$s^2 = \frac{(1.04-1.072)^2 +(1.00-1.072)^2 +(1.13-1.072)^2 +(1.08-1.072)^2 +(1.11-1.072)^2}{5-1}= 0.00277\ approx 0.003$

And thi is the best estimator for the population variance since is an unbiased estimator od the population variance $\sigma^2$

$E(s^2) = \sigma^2$

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3 years ago

Kylie has lemon and watermelon in a ratio of 10:71. How many watermelon does she have if she has 20 lemons

kkurt [141]

Answer:

She will have 142 watermelons

Step-by-step explanation:

First let's put our ratio

10 : 71

Since our lemons are now 20 instead of 10 we will divide 20 by 10 to see how many time we multiplied it by.

$20 \div 10$

which equals 2

To find our water melon we will multiply it by 2

$71 \times 2$

which equals 142

She will have 142 watermelons

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3 years ago

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ASHA 777 [7]

C is the correct answer!

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4 years ago