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2 years ago

A. A number is doubled and then increased by 2, the result is equal to 14 more than

Mathematics

2 answers:

Flauer [41]2 years ago

8 0

❄ Hi there,

let us start by letting the number be r. The problem tells us that r is doubled and then increased by 2.

This is what it looks like –

$\triangleright \ \sf{2r+2}$

Also the result is 14 more than 5r.

We end up with an equation that looks like this –

$\triangleright \ \sf{2r+2=14+5r}$

To find the number we should solve the equation for r –

$\large\begin{gathered} \sf{2r+2=14+5r} . \ Solve \ for \ r: \\ \sf{2r-5r+2=14}\\ \\ \sf{-3r+2=14}\\\sf{-3r=14-2}\\\sf{-3r=12}\\\sf{-r=4}\\\sf{r=-4}\end{gathered}$

❄

Nataly_w [17]2 years ago

4 0

Answer:

Let x=the number

2x=double the number

2x+5=the doubled number increased by 5

And we are told that this equals -47

sooooo

2x+5=-47 subtract 5 from each side2x=-47-5=-52

2x=-52

x=-26------the number

2*(-26)=-52

-52 increased by 5=-52+5=-47

-47=-47

Hope this helps- Clara ☆*: .｡. o(≧▽≦)o .｡.:*☆

Step-by-step explanation:

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allsm [11]

Answer:

$z=1.28$

And if we solve for a we got

$a=3.6 +1.28*0.8=4.624$

So the value of height that separates the bottom 90% of data from the top 10% is 4.624.

So then the best answer for this case would be:

C. 4.64

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the weights of a population, and for this case we know the distribution for X is given by:

$X \sim N(3.6,0.8)$

Where $\mu=3.6$ and $\sigma=0.8$

For this part we want to find a value a, such that we satisfy this condition:

$P(X>a)=0.1$ (a)

$P(X$ (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.

As we can see on the figure attached the z value that satisfy the condition with 0.9 of the area on the left and 0.1 of the area on the right it's z=1.28. On this case P(Z<1.28)=0.9 and P(z>1.28)=0.1

If we use condition (b) from previous we have this:

$P(X$