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dalvyx [7]
3 years ago
13

Previously, an organization reported that teenagers spent 24.5 hours per week, on average, on the phone. The organization thinks

that, currently, the mean is higher. Fifteen randomly chosen teenagers were asked how many hours per week they spend on the phone. The sample mean was 25.7 hours with a sample standard deviation of 2.0. What is the appropriate test to perform?
Mathematics
1 answer:
Lena [83]3 years ago
8 0

Answer:

We need to develop a one-tail t-student test ( test to the right )

We reject H₀  we find evidence that student spent more than 24,5 hours on the phone

Step-by-step explanation:

Sample size  n = 15     n < 30

And we were asked if the mean is higher than, therefore is a one-tail t-student test ( test to the right )

Population mean   μ₀  = 24,5

Sample mean   μ  =  25,7

Sample standard deviation s = 2

Hypothesis Test:

Null Hypothesis      H₀                             μ  =  μ₀

Alternative Hypothesis     Hₐ                  μ  >  μ₀

t (c) =  ?

We will define CI = 95 %  then   α = 5 %   α = 0,05    α/2 =  0,025

n = 15     then degree of freedom    df = 14

From t-student table  we get:  t(c) = 2,1448

And  t(s)

t(s) = ( μ  -  μ₀  ) / s/√n

t(s) = (25,7 - 24,5) /2/√15

t(s) = 2,3237

Now we compare   t(c)   and  t(s)

t(c)  =  2,1448         t(s)  = 2,3237

t(s) > t(c)

Then we are in the rejection region we reject H₀   we have evidence at 95% of CI that students spend more than 24,5 hours per week on the phone

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Simplify the following expression. (10-4i)(4-5i)+(-15+20i)
Vikki [24]

Answer:

5-46i

Step-by-step explanation:

1. Multiply (10-4i) and (4-5i), I recomnd using foil:

40-50i-16+20i^2 + (-15+20i)

2. Remove the parenthesis around -15+20i

*we can do this since there is a "+":    

40-50i-16+20i^2 + (-15)+20

3. Simplify i^2

* i^2 is -1 by textbook defination:

40-50i-16+20(-1) + (-15)+20

4. Simplify

40-50i-16-20 + (-15)+20

6. Combine like terms:

-5-50i-16i+20i

5-46i

And the problem is done

3 0
3 years ago
Please tell me the answer and how to get it. ​
Naddik [55]

Answer:

Unique Triangle

You can think of it visually.

How to get it: The triangle sum theorem, which only allows for unique triangles (depending on the question), can be applied here.

4 0
2 years ago
In the summertime your friend wants to have a snow cone stand at a local grocery store parking lot. You want to make sure he act
Vitek1552 [10]
a) The total monthly cost is the sum of the fixed cost and the variable cost. If q represents the number of cones sold in a month, the monthly cost c(q) is given by 
   c(q) = 300 + 0.25q

b)
If q cones are sold for $1.25 each, the revenue is given by
   r(q) = 1.25q

c)
Profit is the difference between revenue and cost.
   p(q) = r(q) - c(q)
   p(q) = 1.00q - 300
. . . . . . slope-intercept form

d)
The equation in part (c) is already in slope-intercept form.
   q - p = 300
. . . . . . . . . . . . standard form
The slope is the profit contribution from the sale of one cone ($1 per cone).
The intercept is the profit (loss) that results if no cones are sold.

e) With a suitable graphing program either form of the equation can be graphed simply by entering it into the program.
   Slope-intercept form. Plot the intercept (-300) and draw a line with the appropriate slope (1).
   Standard form. It is convenient to actually or virtually convert the equation to intercept form and draw a line through the points (0, -300) and (300, 0) where q is on the horizontal axis.

f) Of the three equations created, we presume the one of interest is the profit equation. Its domain is all non-negative values of q. Its range is all values of p that are -300 or more.

g) The x-intercept identified in part (e) is (300, 0). You need to sell 300 cones to break even.

h) Profit numbers are
   425 cones: $125 profit
   550 cones: $250 profit
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7 0
3 years ago
john read the first 114 pages of a novel which is 3 pages less than 1/3 of the novel. write the equation
tatyana61 [14]

The equation is:

114=\frac{p}{3}-3

And

Total number of pages are 351

Step-by-step explanation:

The equation has to be formed by using the given information.

Let p be the total number of pages in the novel

Then

1/3rd of the p will pe:

\frac{p}{3}

Total pages read by John = 114

Then according to the statement

114=\frac{p}{3}-3

We can solve the equation to get the total pages of the novel

114=\frac{p}{3}-3\\Adding\ 3\ on\ both\ sides\\114+3=\frac{p}{3}-3+3\\117=\frac{p}{3}\\Multiplying\ both\ sides\ by\ 3\\3*117 = \frac{p}{3}*3\\p=351

The equation is:

114=\frac{p}{3}-3

And

Total number of pages are 351

Keywords: Linear equation, variable

Learn more about linear variable at:

  • brainly.com/question/9196410
  • brainly.com/question/9178881

#LearnwithBrainly

8 0
3 years ago
Zina solves a system of linear equations by elimination and finds a solution of (2, 2). One of the equations is a + b = 4. What
Dima020 [189]

Answer:

Option D

a+3b=8

6 0
3 years ago
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