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3 years ago

Use the equation xy= 12.6. Find the value of y when x=7

Mathematics

1 answer:

Marat540 [252]3 years ago

6 0

Answer: y = 1.8

Step-by-step explanation:

xy = 12.6 If x is 7 but 7 in the equation for x

7y = 12.6 Divide both sides by 7

y = 1.8

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Two trains started moving at the same time, train A from Boston to New York, and train B from New York to Boston. The distance b

Ede4ka [16]

Answer:

After 1.7 hours

Explanation:

1. Calculate the average speed of train B

60mph = 3/4 (s) ⇒ s = 60 (4/3) mph = 80 mph

2. Build a table

When the two trains meet:

Train Average speed Distance time (distance/average speed)

mph

A 60 x x/60

B 80 240 - x (240 - x) / 80

3. Write the equation

The time, when the two trains meet, is the same for both trains:

$\dfrac{x}{60}=\dfrac{240-x}{80}\\ \\ \\ 80x=14,400-60x\\ \\ 80x+60x=14,400\\ \\ 140x=14,400\\ \\ x=14,400/140\\ \\ x=102.85miles$

4. Calculate the time:

x/60 = 102.86 / 60 = 1.7 hours

The two trains will meet after 1.7 hours

7 0

3 years ago

You can pack 6 cans in 1 box. Write a proportion to find the number of

seraphim [82]

Answer:

Step-by-step explanation:

You can fit 6 cans in a box. So now there are 12 boxes. Therefore you have to multiply 6 times 12 which should give you 72. You can fit 72 cans in 12 boxes total

6 0

3 years ago

Brewed decaffeinated coffee contains some caffeine. We want to estimate the amount of caffeine in 8 ounce cups of decaf coffee a

rusak2 [61]

Answer:

We would have to take a sample of 62 to achieve this result.

Step-by-step explanation:

Confidence level of 95%.

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

Assume that the standard deviation in the amount of caffeine in 8 ounces of decaf coffee is known to be 2 mg.

This means that $\sigma = 2$

If we wanted to estimate the true mean amount of caffeine in 8 ounce cups of decaf coffee to within /- 0.5 mg, how large a sample would we have to take to achieve this result?

We would need a sample of n.

n is found when $M = 0.5$ . So

$M = z\frac{\sigma}{\sqrt{n}}$

$0.5 = 1.96\frac{2}{\sqrt{n}}$

$0.5\sqrt{n} = 2*1.96$

Dividing both sides by 0.5

$\sqrt{n} = 4*1.96$

$(\sqrt{n})^2 = (4*1.96)^2$

$n = 61.5$

Rounding up

We would have to take a sample of 62 to achieve this result.

8 0

3 years ago

Please help me ASAP!!!

Galina-37 [17]

Answer:

C XD

Step-by-step explanation:

The altitude of a triangle goes from the vertex (corner) to the opposite side. It must be perpendicular to the opposite side ( at a right angle)

XD is an altitude

4 0

3 years ago

0.05555555555 as a simplified fraction. Please, I’m raging so much right now.

Artemon [7]

Answer:

5555555555/100000000000

Step-by-step explanation:

I guess I am not sure though.

Can you help me with my question?

PLS HELP ASAP!!!!

A restaurant wants to study how well it's salads sell. the circle graph shows the sales over the past few days. If 15 of the salads sold were caesar salads, how many total salads did the restaurant sell Caesar 30% Garden 58% Cobb 12%?

5 0

3 years ago

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