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Aloiza [94]
3 years ago
11

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

0 and a standard deviation of 1. Find the probability that a given score is less than negative 0.84 and draw a sketch of the region.

Mathematics
1 answer:
jarptica [38.1K]3 years ago
7 0

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 <em>normally distributed</em> according to a <em>standard normal distribution</em>, that is, a normal distribution with \\ \mu = 0 and \\ \sigma = 1.
  • We are provided with a <em>z-score</em> 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

  • <em>x</em> is the <em>raw value</em> 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 <em>normal distribution</em>.

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

Solving the question

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

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

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

  • Find the <em>cumulative standard normal table.</em>
  • 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 <em>standard normal distribution</em>, \\ N(0,1), at the <em>left</em> of <em>z = -0.84</em>.

To "draw a sketch of the region", we need to draw a normal distribution <em>(symmetrical bell-shaped distribution)</em>, 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 <em>equal parts</em> of <em>one standard deviation</em> 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).

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6 0
2 years ago
Helppppppp pleaseeeeee
ANEK [815]

All you have to do is plug in the number for x, and find y. I will write this out as if in that chart you have shown.

x                            y = 9 - 3x                                    y

_______________________________________

0                           y = 9 - 3(0)                                  9

1                            y = 9 - 3(1)                                   6

2                           y = 9 - 3(2)                                  3

3                           y = 9 - 3(3)                                  0


Hope that helps!!


4 0
3 years ago
Read 2 more answers
HELP ME PLEASE!!
LUCKY_DIMON [66]

Using a system of equation, we have that:

a)

  • x, which is the cost of on-site service.
  • y, which is the cost of at-store service.
  • z, which is the cost of by-mail service.

b)

The system is:

x = 3y

z = y - 10

15x + 40y + 5z = 3100

c)

The cost of one on-site repair service is of $90.

Item a:

The variables are:

  • x, which is the cost of on-site service.
  • y, which is the cost of at-store service.
  • z, which is the cost of by-mail service.

Item b:

On-site service costs <u>3 times as much as at-store service</u>, thus:

x = 3y

By mail service costs <u>$10 less than at-store</u>  service, thus:

z = y - 10

Last week, the shop completed <u>15 services on-site, 40 services at-store, and 5 services by mail for total sales of $3100</u>, thus:

15x + 40y + 5z = 3100

The system is:

x = 3y

z = y - 10

15x + 40y + 5z = 3100

Item c:

  • The cost of one on-site repair service is x.
  • First, replacing the first two equations into the third, we find y, and then with it we find x.

15x + 40y + 5z = 3100

15(4y) + 40y + 5(y - 10) = 3100

60y + 40y + 5y = 3150

105y = 3150

y = \frac{3150}{105}

y = 30

Then

x = 3y = 3(30) = 90

The cost of one on-site repair service is of $90.

A similar problem is given at brainly.com/question/24823220

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2 years ago
IF CORRECT ILLL BIVE U BRAINLIEST NEED FAST PLS
Montano1993 [528]

Answer: The first one -4x-3<13

Step-by-step explanation: because they didn't really tell us what happened to the 3 just that the 3 disappeared and the 13 became 16

5 0
1 year ago
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