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3 years ago

Add first 15 natural numbers and find the average? Solution with formula?

Mathematics

2 answers:

NeTakaya3 years ago

7 0

Good morning ☕️

Answer:

Step-by-step explanation:

the formula : (sum of 15 consecutive term of an arithmetic sequence)

$1+2+3+...+15=\frac{15*(15+1)}{2} =\frac{15*16}{2}=15*8\\$

Now,

$Average=\frac{15*8}{15} =8$

kicyunya [14]3 years ago

5 0

Answer:

120

Step-by-step explanation:

You might be interested in

-3x-y=-17 4x + 2 y equals 20

ExtremeBDS [4]

-3x - y = -17
4x + 2y = 20

multiply one part of the equation so that we can be able to use the process of elimination.

(-3x - y = -17)2
4x + 2y = 20

Now we have:

-6x -2y = - 34
4x+2y= 20
------------------------
-2x = -14

Divide -2 on both sides.

-2x = -14
/-2       /-2

x = -7.

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

To solve for y, we just have to substitute the value of x to any of the equation given above, that we feel comfortable with. And I'm going to choose this equation: 4x + 2y = 20

4x + 2y = 20

4(-7) + 2y = 20

-28 + 2y = 20

Add 28 on both sides

-28 + 2y = 20
+28          +28
---------------------
2y = 48
/2      /2

y = 24.

The last thing you would do is to check if the answers is correct.
All you have to do is plug in the values of x and y into both equations and see if they equal to one another.

You may have to do this by yourself :P

Anyways, if you have any questions about this topic, feel free to PM me or any other users interested. Thank you for being part of Brainly! Have a nice day!

4 0

3 years ago

Mia is finally able to upgrade her cellphone. The one she wants costs $220 but she is able to get it for 60% off. She has a coup

Kay [80]

The answer would be A) $79.20

(220*.4).9 as 60 percent off means that the product is only 40 percent of its original value, furthermore, we multiply the entire thing by .9

8 0

3 years ago

Write a situation to describe the equation below: C=50+16x

kotykmax [81]

Ryan has 50 cookies if he wants to buys x amount of 16 cookies, how many cookies will he have c= cookies

7 0

3 years ago

How much pure acid should be mixed with 6 gallons of a 20% acid solution in order to get a 90% acid solution?

beks73 [17]

So, how much acid is there in 6 gallons? well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.

now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it? well (90/100) * y, or 0.9y.

now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it? (100/100) * x, or 1x or just x.

we know whatever "x" and "y" amounts are, they -> x + 6 = y

and we also know that x + 1.2 = 0.9y

$\bf \begin{array}{lccclll}
&\stackrel{gallons}{acid}&\stackrel{acid~\%}{quantity}&\stackrel{acid~gallons}{quantity}\\
&------&------&------\\
\textit{pure acid}&x&1.00&x\\
\textit{20\% sol'n}&6&0.20&1.2\\
------&------&------&------\\\
mixture&y&0.90&0.9y
\end{array}
\\\\\\
\begin{cases}
x+6=\boxed{y}\\
x+1.2=0.9y\\
----------\\
x+1.2=0.9\left( \boxed{x+6} \right)
\end{cases}
\\\\\\
x+1.2=0.9x+5.4\implies x-0.9x=5.4-1.2\implies 0.1x=4.2
\\\\\\
x=\cfrac{4.2}{0.1}\implies x=\stackrel{gallons}{42}$

3 0

3 years ago

Assume that the empirical rule is a good model for the time it takes for all passengers to board an airplane. The mean time is 4

slamgirl [31]

Answer:

The interval that describes how long it takes for passengers to board the middle 95% of the time is between 40.16 minutes and 55.84 minutes.

Step-by-step explanation:

Problems of normally distributed samples can be 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.

In this problem, we have that:

$\mu = 48, \sigma = 4$ .