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3 years ago

Nine times the sum of a number and 4 is 2

Mathematics

1 answer:

Anna11 [10]3 years ago

7 0

Answer(s):

If you are asking for the equation, it's 9(x+4)=2

However, if you're asking for the value of x as well, it's -34/9

Step by Step:

1) First we must find the equation. In your question, the unknown number is x. Therefore we can know that "the sum of a number and 4" is (x+4). Since we are multiplying this sum by 9, we can put the 9 in front of this expression to multiply it--getting 9(x+4). And since we know it "is 2" we can say that 9(x+4)=2.

2) Now, we have to solve the equation, 9(x+4) = 2

3) We can start by distributing, 9x+36 = 2

4) Now let's move 36 to the right by subtracting from both sides, 9x = -34

5) To isolate x, let's divide both sides by 9, x = -34/9

6) Our fraction answer can't be simplified, so we get x = -34/9

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4- A manufacturing process produces items whose weights are normally distributed. It is known that 22.57% of all the items produ

galben [10]

Answer:

$\\ \mu = 118\;grams\;and\;\sigma=30\;grams$

Step-by-step explanation:

We need to use z-scores and a standard normal table to find the values that corresponds to the probabilities given, and then to solve a system of equations to find $\\ \mu\;and\;\sigma$ .

<h3>First Case: items from 100 grams to the mean</h3>

For finding probabilities that corresponds to z-scores, we are going to use here a <u>Standard Normal Table </u><u><em>for cumulative probabilities from the mean </em></u><em>(Standard normal table. Cumulative from the mean (0 to Z), 2020, in Wikipedia) </em>that is, the "probability that a statistic is between 0 (the mean) and Z".

A value of a z-score for the probability P(100<x<mean) = 22.57% = 0.2257 corresponds to a value of z-score = 0.6, that is, the value is 0.6 standard deviations from the mean. Since this value is <em>below the mean</em> ("the items produced weigh between 100 grams up to the mean"), then the z-score is negative.

Then

$\\ z = -0.6\;and\;z = \frac{x-\mu}{\sigma}$

$\\ -0.6 = \frac{100-\mu}{\sigma}$ (1)

<h3>Second Case: items from the mean up to 190 grams</h3>

We can apply the same procedure as before. A value of a z-score for the probability P(mean<x<190) = 49.18% = 0.4918 corresponds to a value of z-score = 2.4, which is positive since it is after the mean.

Then

$\\ z =2.4\;and\; z = \frac{x-\mu}{\sigma}$

$\\ 2.4 = \frac{190-\mu}{\sigma}$ (2)

<h3>Solving a system of equations for values of the mean and standard deviation</h3>

Having equations (1) and (2), we can form a system of two equations and two unknowns values:

$\\ -0.6 = \frac{100-\mu}{\sigma}$ (1)

$\\ 2.4 = \frac{190-\mu}{\sigma}$ (2)

Rearranging these two equations:

$\\ -0.6*\sigma = 100-\mu$ (1)

$\\ 2.4*\sigma = 190-\mu$ (2)

To solve this system of equations, we can multiply (1) by -1, and them sum the two resulting equation:

$\\ 0.6*\sigma = -100+\mu$ (1)

$\\ 2.4*\sigma = 190-\mu$ (2)

Summing both equations, we obtain the following equation:

$\\ 3.0*\sigma = 90$

Then

$\\ \sigma = \frac{90}{3.0} = 30$

To find the value of the mean, we need to substitute the value obtained for the standard deviation in equation (2):

$\\ 2.4*30 = 190-\mu$ (2)

$\\ 2.4*30 - 190 = -\mu$

$\\ -2.4*30 + 190 = \mu$

$\\ \mu = 118$

7 0

3 years ago

What is the area of this face?

SSSSS [86.1K]

Answer:

Hello! answer: 180

Step-by-step explanation:

what I did to find answer is cut them into pieces I cut the m into 3 pieces and now just have to multiply my base x height so for the left one I did 12 x 6 = 72 for the middle I did 6 x 6 = 36 and for the right one I did 12 x 6 = 72 I add these up so...

72 + 36 + 72 = 180 so the surface area is 180! I hope this helps!

4 0

2 years ago

Write in standard form. a) 2 4 b) 10 3 c) 3 5 d) 7 3 e) 2 8 f) 4 1 <br><br> PLZ HELP!!!!!

Rama09 [41]