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Oksanka [162]
3 years ago
14

A national dental association conducted a survey to find the average (mean) amount of time dentists spend on dental fillings per

week. Based on a simple random sample, they surveyed 144 dentists. The statistics showed that dentists spent an average of 20 hours per week on fillings with a standard deviation of 10 hours. What is the probability of finding a sample mean less than 18 hours?
Mathematics
1 answer:
eduard3 years ago
4 0

Answer:

The probability of finding a sample mean less than 18 hours is 0.0082

Step-by-step explanation:

To find the probability of finding a sample mean less than 18 hours, we need to calculate the z-score of this sample mean 18. And the probability of finding a sample mean less than 18 hours is P(z<z(18)).

Z-score can be calculated as follows:

z(18)=\frac{X-M}{\frac{s}{\sqrt{N} } } where

  • X is the sample mean (18 hours)
  • M is the average hours dentists spend per week on fillings (20 hours)
  • s is the standard deviation (10 hours)
  • N is the sample size (144)

Putting the numbers, we get:

z(18)=\frac{18-20}{\frac{10}{\sqrt{144} } }=-2.4

Using z- table we can find that P(z<z(18)) = 0.0082

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6 0
3 years ago
!PLEASE HELP!<br>Solve for MN. <br><br>A) 21 <br><br>B)9 <br><br>C)6 <br><br>D)4
Oksanka [162]

The measure of MN from the diagram is 6

<h3>Similarity theorem of triangles</h3>

From the given triangle, the expression below is true;

ML/LK = MN/NO

Given the following parameters

ML = 4

LK = 10

NO= 15

Substitute the given parameters into the formula

4/10 = MN/15

Cross multiply

10MN = 4 * 15

10MN = 60

MN = 6

Hence the measure of MN from the diagram is 6

Learn more on similar triangles here: brainly.com/question/14285697

7 0
2 years ago
MAX POINTS!!! Write and solve a system of equations. Be sure to label the variables. The difference of two numbers is two. Two t
Cerrena [4.2K]

Answer:

  • 5 and 3

Step-by-step explanation:

Let the numbers be x and y.

<u>The equations are:</u>

  • x - y = 2
  • 2x + y = 13

<u>Add up the equations to eliminate y and solve for x:</u>

  • x - y + 2x + y = 2 + 13
  • 3x = 15
  • x = 15/3
  • x = 5

<u>Now find the value of y:</u>

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3 0
3 years ago
Read 2 more answers
17
Aleksandr-060686 [28]

Answer:

The expressions that give the value of y are A - 3B and (1/3)A - B

The solution is (27/13, -60/13)

Step-by-step explanation:

We can see both equation A and equation B.

Equation A: 2x + (1/4)y = 3

Equation B: (2/3)x - y = 6

To find the value of y, we have to solve both equations A and equation B simultaneously. This is done by multiplying equation B by 3 and subtracting from equation A (A - 3B) to get:

(13/4)y = -15

y = -60/13

you can also get y by dividing equation A by 3 and subtracting equation B (1/3A - B)

Put y = -60/13 in equation A to get x:

2x + (1/4)(-60/13) = 3

2x = 3 + 15/13

2x = 54/13

x = 27/13

The solution is (27/13, -60/13)

7 0
3 years ago
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Aloiza [94]
You sure this is a elentary question
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