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3 years ago

This is my question. If Andy drove 840 miles in 12 hours. How far could he drive in hours? Help me?

Mathematics

1 answer:

stellarik [79]3 years ago

7 0

Answer:

840mi. - 12 hrs

x - 3 hrs

This is a simple cross multiplying problem.

840 _ 12

x -- 3 ⇒12x=3(840) ⇒ 4x=280 ⇒ x=70 miles

Step-by-step explanation:

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Some types of algae have the potential to cause damage to river ecosystems. Suppose the accompanying data on algae colony densit

Phantasy [73]

Answer:

$y=-2.95836 x +234.56159$

Step-by-step explanation:

We assume that th data is this one:

x: 50, 55, 50, 79, 44, 37, 70, 45, 49

y: 152, 48, 22, 35, 43, 171, 13, 185, 25

a) Compute the equation of the least-squares regression line. (Round your numerical values to five decimal places.)For this case we need to calculate the slope with the following formula:

$m=\frac{S_{xy}}{S_{xx}}$

Where:

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}$

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}$

So we can find the sums like this:

$\sum_{i=1}^n x_i =50+ 55+ 50+ 79+ 44+ 37+ 70+ 45+ 49=479$

$\sum_{i=1}^n y_i =152+ 48+ 22+ 35+ 43+ 171+ 13+ 185+ 25=694$

$\sum_{i=1}^n x^2_i =50^2 + 55^2 + 50^2 + 79^2 + 44^2 + 37^2 + 70^2 + 45^2 + 49^2=26897$

$\sum_{i=1}^n y^2_i =152^2 + 48^2 + 22^2 + 35^2 + 43^2 + 171^2 + 13^2 + 185^2 + 25^2=93226$

$\sum_{i=1}^n x_i y_i =50*152+ 55*48+ 50*22+ 79*35+ 44*43+ 37*171+ 70*13+ 45*185+ 49*25=32784$

With these we can find the sums:

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=26897-\frac{479^2}{9}=1403.556$

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}=32784-\frac{479*694}{9}=-4152.22$

And the slope would be:

$m=-\frac{-4152.222}{1403.556}=-2.95836$

Nowe we can find the means for x and y like this:

$\bar x= \frac{\sum x_i}{n}=\frac{479}{9}=53.222$

$\bar y= \frac{\sum y_i}{n}=\frac{694}{9}=77.111$

And we can find the intercept using this:

$b=\bar y -m \bar x=77.1111111-(-2.95836*53.22222222)=234.56159$

So the line would be given by:

$y=-2.95836 x +234.56159$

7 0

2 years ago

The next train will arrive in 32 minutes and 30 seconds. In how many seconds will the next train arrive

sineoko [7]

You need to multiply the 30 with the 32

4 0

2 years ago

Read 2 more answers

Help ASAP please !! No scam I really need this<br> Trigonometry!!

USPshnik [31]

<h3>Answer: Choice D) 7.5 cm</h3>

==========================================================

Explanation:

We are told that quadrilateral ABCD is similar to quadrilateral EFGH.

The order of the four letter sequence is important.

For ABCD, we have AB as the first pair of letters.
For EFGH, we have EF as the first pair of letters.

Therefore, AB and EF are corresponding sides.

So AB = 10 and EF = x pair up together. We can form the ratio AB/EF which becomes 10/x.

The diagram shows that AD = 8. Notice that A and D are the first and last letters of ABCD. The first and last letters of EFGH are E and H. We can see that AD and EH correspond to one another because of this.

AD = 8 and EH = 6 forming the ratio AD/EH = 8/6

Because the quadrilaterals are similar, the corresponding ratios must be the same. Therefore, AB/EF is the same as AD/EH.

-----------------------

Let's set up a proportion to solve for x

AB/EF = AD/EH

10/x = 8/6

10*6 = x*8

60 = 8x

8x = 60

x = 60/8

x = 7.5 Answer is choice D

6 0

2 years ago

Solve the math problem

Nadusha1986 [10]

<u>Answer:</u>

Below!

<u>Explanation:</u>

Exponents are small numbers that defines how many times does the base needs to multiply itself. Two exponents can also be classified in words. 'Squared' defines a number multiplying itself two times. 'Cubed' defines a number multiplying itself three times. If there is a zero as the base's exponent, this means that the result will always be 1. Now, let's solve all the problems together.

2¹ = 2
3⁵ = 3 x 3 x 3 x 3 x 3 = 243
4³ = 4 x 4 x 4 = 64
6⁴ = 6 x 6 x 6 x 6 = 1256
7⁴ = 7 x 7 x 7 x 7 = 2401
1⁶ = 1 x 1 x 1 x 1 x 1 x 1 = 1
8² = 8 x 8 = 64
2³ = 2 x 2 x 2 = 8
4⁴ = 4 x 4 x 4 x 4 = 256
10³ = 10 x 10 x 10 = 1000
12² = 12 x 12 = 144
5⁴ = 5 x 5 x 5 x 5 = 625
6² = 6 x 6 = 36
3⁶ = 3 x 3 x 3 x 3 x 3 x 3 = 729
7³ = 7 x 7 x 7 = 343
2⁴ = 2 x 2 x 2 x 2 = 16
11⁰ = 1
4³ = 4 x 4 x 4 = 64
1¹² = 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x 1 = 1

Hoped this helped!

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2 years ago

Give an estimate of the mean hardness that you would expect after 37 and 41 hours; and a 85% confidence interval for each estima

Jlenok [28]

The predicted value of hardness at 37 hours is 243.87 and an 85% confidence interval for the mean hardness is (242.12, 245.61). At 41 hours, the predicted hardness is 252 and an 85% confidence interval for mean hardness is (249.83, 254.18). The confidence interval for X is equals to 41 which is wider because the value 41 is farther away from the sample mean X than is 37. As an outcome, the standard error for the prediction is larger.

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3 years ago