9 multiplied by 21 equals what

Airida [17]

To find a percentage of a number we multiply the percentage times the number and get the result, here we have the percentage and the result and need to find out which number it corresponds to, lets write an equation to do so and keep in mind that the percentage itself can be written in a different way:
225% = 225 out of 100 = 225/100
So we have this equation, where we call x the number we are looking for:
(225%)(x) = 81
(225/100)(x) = 81
so we solve for x:
225x = 81*100 = 8100
x = 8100/225
x = 36
The original number is 36, hence 225% of 36 is 81

4 0

3 years ago

Assume that a randomly selected subject is given a bone density test. Those test scores are normally distributed with a mean of

jarptica [38.1K]

Answer:

The "probability that a given score is less than negative 0.84" is $\\ P(z$ .

Step-by-step explanation:

From the question, we have:

The random variable is normally distributed according to a standard normal distribution, that is, a normal distribution with $\\ \mu = 0$ and $\\ \sigma = 1$ .
We are provided with a z-score of -0.84 or $\\ z = -0.84$ .

Preliminaries

A z-score is a standardized value, i.e., one that we can obtain using the next formula:

$\\ z = \frac{x - \mu}{\sigma}$ [1]

Where

x is the raw value coming from a normal distribution that we want to standardize.
And we already know that $\\ \mu$ and $\\ \sigma$ are the mean and the standard deviation, respectively, of the normal distribution.

A z-score represents the distance from $\\ \mu$ in standard deviations units. When the value for z is negative, it "tells us" that the raw score is below $\\ \mu$ . Conversely, when the z-score is positive, the standardized raw score, x, is above the mean, $\\ \mu$ .

Solving the question

We already know that $\\ z = -0.84$ or that the standardized value for a raw score, x, is below $\\ \mu$ in 0.84 standard deviations.

The values for probabilities of the standard normal distribution are tabulated in the standard normal table, which is available in Statistics books or on the Internet and is generally in cumulative probabilities from negative infinity, - $\\ \infty$ , to the z-score of interest.

Well, to solve the question, we need to consult the standard normal table for $\\ z = -0.84$ . For this:

Find the cumulative standard normal table.
In the first column of the table, use -0.8 as an entry.
Then, using the first row of the table, find -0.04 (which determines the second decimal place for the z-score.)
The intersection of these two numbers "gives us" the cumulative probability for z or $\\ P(z$ .

Therefore, we obtain $\\ P(z$ for this z-score, or a slightly more than 20% (20.045%) for the "probability that a given score is less than negative 0.84".

This represent the area under the standard normal distribution, $\\ N(0,1)$ , at the left of z = -0.84.

To "draw a sketch of the region", we need to draw a normal distribution (symmetrical bell-shaped distribution), with mean that equals 0 at the middle of the distribution, $\\ \mu = 0$ , and a standard deviation that equals 1, $\\ \sigma = 1$ .

Then, divide the abscissas axis (horizontal axis) into equal parts of one standard deviation from the mean to the left (negative z-scores), and from the mean to the right (positive z-scores).

Find the place where z = -0.84 (i.e, below the mean and near to negative one standard deviation, $\\ -\sigma$ , from it). All the area to the left of this value must be shaded because it represents $\\ P(z$ and that is it.

The below graph shows the shaded area (in blue) for $\\ P(z$ for $\\ N(0,1)$ .

7 0

3 years ago

A new cell tower is being constructed and needs a guy-wire connected 180 feet up the tower and it needs to make an angle of 52°

nevsk [136]

Answer:

228.42 ft

Step-by-step explanation:

To solve for this question, we would be applying the Trigonometric function of Sine.

Sin theta = Opposite/Hypotenuse

Theta = 52°

Opposite = 180ft

Hypotenuse = Length of the wire = x

Hence:

sin 52 = 180/x

x = 180/sin 52

x = 228.42327871 ft

Approximately = 228.42 ft

6 0

2 years ago

Write the equation of a line that is perpendicular to the line that passes through (4,−3)and (−7,8).

masha68 [24]

Line perpendicular to a given line is = 1/m

To find m, use m =y2-y1/x2-x1 formula

m = (8-(-3))/(-7-4)

m = 11/-11,

m = -1

Use y= mx+c to find equation of line

Plug in a pair of values,

-3= -1(4)+ c

c= 1

Thus, equation is:

y = -x+1

Equation of line perpendicular to this line is:

y= x+1

Hope it helps :)

Pls mark it as Brainliest :)

3 0

2 years ago

Find The surface area of the cylinder. round your answer to the nearest tenth

trasher [3.6K]

Answer:

791.7

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6 0

2 years ago