Mathematics, 14.01.2020 05:31 anme3c9

Five students took a test in their math class. the scored a 72, 56, 77, 69, and x. what did the fifth student have to score in order to have a class average of a 71.

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Answer from: abelgutierrez370

Step-by-step explanation:

If the class average needs to be 71, the mean has to be 71. (Mean is a type of average btw).

Formula to find the mean: Add up all the values and divide by the amount of values there are.

Since there is an unknown we need to work backwards to find out what it must be so that the mean is 71.

This is what the equation would look like.

(71 + 56 + 77 + 69 + x) / 5 = 71

But, to find x we need to make x the subject of the equation, this means that x needs to be on its own at one side of the equals sign so that we have a formula that equals to x. Then we can just do that formula and work it out.

Making x the subject:

71 + 56 + 77 + 69 + x / 5 = 71

1. Move the '/5' to the other side of the equation. This means it will become a '×5'

71 + 56 + 77 + 69 + x = 71×5

2. Get rid of all the other numbers. We can do this all at once by adding them all together and bringing them to the other side.

273 + x = 71×5

x = (71×5) - 273

Now we have our formula

Working this out:

x = (71×5) - 273

x = 355 - 273

x = 82

The fifth student scored an 82.

Let's check to see

In order to this, find the mean of the values and see if we get 71 to match the question.

(72 + 56 + 77 + 69 + 82) / 5 = 71

356 / 5 = 71.2

Correct!

Answer from: Quest

$r(x)=-\frac{1}{50}x^2+14x$

step-by-step explanation:

let's assume

number of candles set =x

price of of x candles =p(x)

we are given

a candle maker prices one set of scented candles at $10 and sells an average of 200 sets each week

so, we get point as (200,10)

$x=200,p=10$

he finds that when he reduces the price by $1, he then sells 50 more candle sets each week

so, we can find slope

$m=-\frac{1}{50}$

now, we can use point slope form of line

$p(x)=mx+b$

now, we can plug values

$p(x)=-\frac{1}{50}x+b$

we can use point

$x=200,p=10$

and find b

$10=-\frac{1}{50}\times 200+b$

$10=-4+b$

$b=14$

now, we can plug it back

and we get

$p(x)=-\frac{1}{50}x+14$

now, we can find revenue

we know that

revenue = price*quantity

so, we get

$r(x)=x\times p(x)$

$r(x)=x\times (-\frac{1}{50}x+14)$

$r(x)=-\frac{1}{50}x^2+14x$

Answer from: Quest

8p+(-9)

(-9)3p+5p and you can swith em around

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Five students took a test in their math class. the scored a 72, 56, 77, 69, and x. what did the fift...

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