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3 years ago

Help me iwht this one please

Mathematics

1 answer:

EleoNora [17]3 years ago

8 0

Answer:

x = -15

Step-by-step explanation:

In fractional equations we cross multiply the expressions:

In cross multiplying the denominator of the first fraction is multiplied with the numerator of the second fraction and vice versa:

-2x = 30 divide both sides by -2

x = -15

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Adimas found the mean of her 11 math test scores for the first semester. X = StartFraction (76 87 65 88 67 84 77 82 91 85 90) Ov

Reika [66]

To find the solution we will first find the difference between each number and mean, and then substitute the value in the formula of standard deviation.

The standard deviation is 8.4477 and the variance is 71.40.

Given to us

Test scores of Adimas = (76, 87, 65, 88, 67, 84, 77, 82, 91, 85, 90)
Mean = 81

<h3>Standard Deviation</h3>

difference between each number and mean,

$x_1 -\mu= 76-81 = -5\\
x_2-\mu = 87-81 = 6\\
x_3-\mu = 65-81 = -16\\
x_4-\mu = 88 -81 = 7\\
x_5-\mu = 67-81 = -14\\
x_6 -\mu= 84-81 = 3\\
x_7 -\mu= 77-81 = -4\\
x_8 -\mu= 81-81 = 1\\
x_9 -\mu= 91-81 = 10\\
x_{10}-\mu=85-81 = 4\\
x_{11} -\mu= 90-81 = 9$

$\sum(x-\mu)^2 = x_1^2+x_2^2+x_3^2+x_4^2+x_5^2+x_6^2+x_7^2+x_8^2+x_9^2+x_{10}^2+x_{11}^2$

= 25 + 36 + 256 + 49 + 196 + 9 + 16 + 1 + 100 +16 + 81

= 785

$\rm{ Standard\ Deviation = \sqrt{\dfrac{\sum{(X-\mu)^2}} {n}$

$\sigma= \sqrt{\dfrac{785}{11}}\\\\
\sigma = 8.4477$

<h3>Variance</h3>

Variance = $\sigma ^2$

= 71.40

Hence, the standard deviation is 8.4477 and the variance is 71.40.

Learn more about Standard Deviation:

brainly.com/question/12402189

3 0

3 years ago

the ratio of boys to girls in a homeroom at berkmar middle school is 3;4 if there are 12 boys how many girls are in homeroom

REY [17]

Answer:

16 girls

Step-by-step explanation:

If you have 12 boys, and the ratio is 3;4, that means you multiplied 3 times 4. To find the answer to this problem, you need to multiply 4 by 4 because you multiplied 3 by 4, and you always have to multiply or divide by the same thing if its a ratio.

3 0

3 years ago

Help me or I ask 911

OLga [1]

I think it’s B
So sorry if it’s wrong
Recommend a show for you to watch it’s criminal minds

3 0

3 years ago

Read 2 more answers

Find the slope of the equation that goes through:<br> (-4,-14) and (-10,6)

sukhopar [10]

Hello.

In order to find the slope of the given line, we should use the slope formula:

$\mathrm{\displaystyle\frac{y2-y1}{x2-x1}}$

y₂= the y-coordinate of the second point (6

y₁= the y-coordinate of the first point (-14)

x₂=the x-coordinate of the second point (-10)

x₁=the x-coordinate of the first point (-4)

Let's plug in the values and solve:

$\mathrm{\displaystyle\frac{6-(-14)}{-10-(-4)}=\frac{6+14}{-10+4} =\frac{20}{-6} =-\frac{20}{6} =-\frac{10}{3} }$

Answer:

$\Large\boxed{\sf{\displaystyle-\frac{10}{3} }}$

I hope it helps.

Have a nice day.

$\boxed{imperturbability}$

6 0

3 years ago

A recent college graduate is in the process of deciding which one of three graduate schools he should apply to. He decides to ju

romanna [79]

Answer:

For this case after conduct the ANOVA procedure they got an statistic of:

$F = 8.61$

With a p value of :

$p_v =P(F_{2,15} > 8.61) = 0.003$

Since the p value is lower than the significance level $\alpha=0.1$

We can reject the null hypothesis that the means are equal at the significance level provided.

$t = \frac{\bar X_i -\bar X_j}{s_p \sqrt{\frac{1}{n_i} +\frac{1}{n_j}}}$

For school 1 and 2 we have:

$t = \frac{646.7 -606.7}{52.54 \sqrt{\frac{1}{6} +\frac{1}{6}}}= 1.318$

For school 1 and 3

$t = \frac{646.7 -523.3}{52.54 \sqrt{\frac{1}{6} +\frac{1}{6}}}= 4.068$

For school 2 and 3 we have:

$t = \frac{606.7 -523.3}{52.54 \sqrt{\frac{1}{6} +\frac{1}{6}}}= 2.749$

So as we can see we have significant difference between the means of school 1 and 3, and school 2 and 3

Step-by-step explanation:

Previous concetps

Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".

The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"

Solution to the problem

The hypothesis for this case are:

Null hypothesis: $\mu_{1}=\mu_{2}=\mu_{3}$

Alternative hypothesis: Not all the means are equal $\mu_{i}\neq \mu_{j}, i,j=1,2,3$

If we assume that we have $p$ groups and on each group from $j=1,\dots,p$ we have $n_j$ individuals on each group we can define the following formulas of variation: