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3 years ago

18

Mathematics

1 answer:

Alla [95]3 years ago

6 0

Answer:

40x30= 1200, 20x15=300, 300/1200= 1/4.

Step-by-step explanation:

You can also visualize it. Imagine a field 40’ long and the boy cut the top 20’ of it but left 20’ of the bottom, he would have cut half of it at this point. Now it’s 30’ wide and he cut the left 15’ of what’s remaining but left the right 15’ uncut. So now there’s a 20’x15’ bottom right corner left uncut. There are 4 sections that are 20’x15’ and he left one out of four uncut, otherwise written as 1/4.

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How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 95% confidence that

zimovet [89]

Answer:

61 commuters must be randomly selected to estimate the mean driving time of Chicago commuters.

Step-by-step explanation:

Given : We want 95% confidence that the sample mean is within 3 minutes of the population mean, and the population standard deviation is known to be 12 minutes.

To find : How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters?

Solution :

At 95% confidence the z-value is z=1.96

The sample mean is within 3 minutes of the population mean i.e. margin of error is E=3 minutes

The population standard deviation is s=12 minutes

n is the number of sample

The formula of margin of error is given by,

$E=\frac{s\times z}{\sqrt{n}}$

Substitute the value in the formula,

$3=\frac{12\times 1.96}{\sqrt{n}}$

$3=\frac{23.52}{\sqrt{n}}$

$\sqrt{n}=\frac{23.52}{3}$

$\sqrt{n}=7.84$

Squaring both side,

$n=61.4656$

Therefore, 61 commuters must be randomly selected to estimate the mean driving time of Chicago commuters.

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3 years ago

Read 2 more answers

Answers to page 691-693 #1-30

nadezda [96]

What book do you need these answers from?

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3 years ago

Find the missing side lengths. Leave your answers as radicals in simplest form. Show your work to support your answer

kotegsom [21]

Answer

x=2 and y=2√2

Step-by-step explanation:

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3 years ago

Solve for x and y

bekas [8.4K]

Answer:

x = 2√2

y = 2√6

Step-by-step explanation:

Consider the ratio of the two legs of the two smaller interior right triangles. (refer to attached diagrams for the triangles - I have outlined one in blue and the other in red)

These will be equal since the triangles are similar

shorter leg : longer leg

(blue triangle = red triangle)

⇒ x : 4 = 2 : x

⇒ x/4 = 2/x

⇒ x² = 8

⇒ x = √8

⇒ x = 2√2

Now we have x, we have the two legs of the right triangle with hypotenuse labelled y.

Using Pythagoras' Theorem a² + b² = c² (where a and b are the legs and c is the hypotenuse)

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⇒ y² = 24

⇒ y = √24

⇒ y = 2√6

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2 years ago