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3 years ago

-2x-3y=-7 y+1=x solve for y and x

Mathematics

1 answer:

sertanlavr [38]3 years ago

4 0

Answer:

x = 2 and y = 1

Step-by-step explanation:

First, solve for y by substituting the second equation as x into the first equation

-2x - 3y = -7

-2(y + 1) - 3y = -7

Simplify and solve for y

-2y - 2 - 3y = -7

-5y - 2 = -7

-5y = -5

y = 1

Solve for x by plugging in 1 into the second equation

y + 1 = x

1 + 1 = x

2 = x

So, the answer is x = 2 and y = 1

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Margaret [11]

Hello there! I can help you! So there is one blue counter added to two green counters. To solve this problem, we can write and solve an equation. Set it up like this:

12 + 1x = 8 + 2x

We do this, because there are already some of each color in the bag. 1x makes one counter each and 2x is two counters for every blue counter in the bag. Let's solve it. Subtract 1x from each side. 1x - 1x cancels out. 2x - 1x is 1x or just simply x. That simplifies to 12 = 8 + x. Subtract 8 from each side to get the variable by itself. 8 - 8 cancels out. 12 - 8 is 4. That leaves 4 = x. Nothing else needs to be done. Let's plug the value in and see if it works. 1 * 4 is 4. 12 + 4 is 16. 2 * 4 is 8. 8 + 8 is 16. 16 = 16. There. x = 4. 4 blue counters and 8 green counters were added to the bag.

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3 years ago

The following temperatures were recorded in Pasadena for a week in April: 87, 85, 80, 78, 83, 86, 90. Determine the interquartil

Lubov Fominskaja [6]

Answer:

Step-by-step explanation:

87 - 80 = 7

7 0

3 years ago

There are 50 students in a calculus class. The amount of time needed for the instructor to grade a randomly chosen midterm exam

natta225 [31]

Answer:

14.46% probability that the instructor can finish grading in 4 and a half hours

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 normally distributed samples are solved using the z-score formula.

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

Central Limit Theorem

The Central Limit Theorem estabilishes 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.

For sums of n values from a distribution, the mean is $n\mu$ and the standard deviation is $s = \sqrt{n}\sigma$

In this problem, we have that:

$\mu = 6*50 = 300, s = \sqrt{50}*4 = 28.2843$

What is the probability that the instructor can finish grading in 4 and a half hours

Four and half hours is 4.5*60 = 270.

So this probability is the pvalue of Z when X = 270.

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

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{270 - 300}{28.2843}$

$Z = -1.06$

$Z = -1.06$ has a pvalue of 0.1446

14.46% probability that the instructor can finish grading in 4 and a half hours

8 0

3 years ago

Because she has limited shelf space, she can't put out all her copies of the CD at once. On Monday morning, she stocked the disp

fenix001 [56]

Now, it look like there is some information missing in the answer. The whole problem should look like this:

Alicia Keys's new album As I Am is climbing the charts, and the manager of Tip Top Tunes expects to sell a lot of copies. Because she has limited shelf space, she can't put out all her copies of the CD at once. On Monday morning, she stocked the display with 40 copies. By the end of the day, some of the copies had been sold. On Tuesday morning, she counted the number of copies left and then added that many more to the shelf. In other words, she doubled the number that was left in the display. At the end of the day, she discovered that she had sold the exact same number of copies as had been sold on Monday. On Wednesday morning, the manager decided to triple the number of copies that had been left in the case after Tuesday. Amazingly, she sold the same number of copies on Wednesday as she had on each of the first two days! But this time, at the end of the day the display case was empty. How many copies of the As I Am CD did she sell each day?

Answer:

She sold 24 copies of the cd each day.

Step-by-step explanation:

In order to solve this problem we must first set our variable up. In this case, since we need to know what the number of sold cd's per day is, that will just be our variable:

x= Number of copies sold.

So we can start setting our equation up. So we take the first part of the problem:

"On Monday morning, she stocked the display with 40 copies. By the end of the day, some of the copies had been sold."

This can be translated as:

40-x

where this expression represents the number of copies left on the shelf by the end of monday.

"On Tuesday morning, she counted the number of copies left and then added that many more to the shelf."

so we represent it like this:

(40-x)+(40-x)

"In other words, she doubled the number that was left in the display."

so the previous expression can be simplified like this:

2(40-x)

"At the end of the day, she discovered that she had sold the exact same number of copies as had been sold on Monday."

so the expression now turns to:

2(40-x)-x this is the number of copies left by the end of tuesday.

"On Wednesday morning, the manager decided to triple the number of copies that had been left in the case after Tuesday."

this translates to:

3[2(40-x)-x]

This is the number of copies on the shelf by the begining of Wednesday.

"Amazingly, she sold the same number of copies on Wednesday as she had on each of the first two days! But this time, at the end of the day the display case was empty."

this piece of information lets us finish writting our equation:

3[2(40-x)-x] -x = 0

since there were no copies left on the shelf, then the equation is equal to zero.

So now we proceed and solve the equation for x:

3[2(40-x)-x] -x = 0

We simplify it from the inside to the outside.

3[80-2x-x]-x=0

3[80-3x]-x = 0

we now distribute the 3 so we get:

240-9x-x=0

we combine like terms so we get:

240-10x=0

we move the 240 to the other side of the equation so we get:

-10x=-240

and divide both sides into -10 so we get:

x=24

so she sold 24 copies each day.

5 0

4 years ago

A ceiling 6 feet by 7 feet can be painted for $52. find the cost of painting a ceiling 18 feet by 21 feet, all things being equa

kykrilka [37]

6 feet * 7 feet = 42 feet²

18 feet * 21 feet = 378 feet²

42 feet² was painted for $52

1 feet² will be painted for $52/42

378 feet² will then be painted for: ($52/42) * 378

= $468

Hence 18 feet by 21 feet will be painted for $468

Hope this helps.

5 0

3 years ago