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noname [10]
3 years ago
15

Due Wed 10/21/2020 11:30 po

Mathematics
1 answer:
Bezzdna [24]3 years ago
6 0

Answer:

MARK AS BRAINLIST

w = 4

L = 7

Step-by-step explanation:

L = length of rectangle

w = width of rectangle

L = 3 + w

A = 28

A = L*w

=(3+w) * w

28 = 3w + w^2

w^2 + 3w - 28 = 0

w^2 + 7w - 4w - 28 = 0

w ( w + 7 ) - 4 ( w + 7 ) =0

( w - 4 ) ( w + 7 ) = 0

w = 4. and w = -7

take the postive value, w = 4

therefore L= 3+4 = 7

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If y/z=4/7, then z/y=
topjm [15]

Answer:

z/y = 7/4

Step-by-step explanation:

In y/z = 4/7, the numerator and denominator correspond with each other

So, y =4 and z = 7

5 0
2 years ago
The weight of the rectangle is 80
Helga [31]

Answer:

6 2/3

Step-by-step explanation:

7 0
3 years ago
A researcher wishes to​ estimate, with 99​% ​confidence, the population proportion of adults who think the president of their co
scoray [572]

Answer:

a. n=4148

b. n=3909

c. The sample size is smaller if a known proportion from prior study is used. The difference in sample sizes is 239

Step-by-step explanation:

a. For sample where no preliminary estimate is given, the minimum sample size is calculated using the formula:

n=p(1-p)(\frac{z}{ME})^2

Where:

  • ME=Margin of error
  • p= is the assumed proportion

#Let p=0.5, substitute in the formula to solve for n:

n=0.5(1-0.5)\times (2.576/0.02)^2\\\\=4147.36\approx 4148

Hence, the minimum sample size is 4148

b. If given a preliminary estimate p=0.38, we use the same formula but substitute p with the given value:

n=p(1-p)(z/ME)^2\\\\=0.38(1-0.38)(2.576/0.02)^2\\\\=3908.47\approx3909

Hence, the minimum sample size is 3909

c. Comparing the sample sizes from a and b:

n_{0.5}>n_{0.38}\\\\n_{0.5}-n_{0.38}=4148-3909=239

Hence, the actual sample size is smaller for a known proportion from prior a prior study.

8 0
3 years ago
The following frequency table summarizes the number of children that dads in Dads Club have.
attashe74 [19]

Answer:

C

Step-by-step explanation:

Now there are 6+4+8+1+1=20 dads in the Dads Club.

Fewer than 3 children have

  • 1 child - 6 dads
  • 2 children - 4 dads.

So, 6+4=10 dads have fewer than 3 children.

The probability that the dad of Dads Club has fewer than 3 children is

Pr=\dfrac{10}{20}=0.5 \text{ or } 50\%.

The probability that the next dad to join Dads Club has fewer than 3 children is reasonable to be 50%.

8 0
3 years ago
Read 2 more answers
Calculate the average rate of change of f(x) over the interval [-4, -1] using the formula [ BLANK ] The value of f(-1) is [BLANK
lesantik [10]
Answers:
The formula is [f(-1)-f(-4)]/[3]
The value of f(-1) is 3
The value of f(-4) is -3
The average rate of change is 2

==============================================

Explanation:

For the first blank, we use the formula
[ f(b) - f(a) ]/[ b - a ]
where 'a' and 'b' are the endpoints for the x interval

In this case, a = -4 and b = -1. When you plug those values into the formula above, you get...
[ f(b) - f(a) ]/[ b - a]
[ f(-1) - f(-4)]/[ -1 - (-4) ] 
[ f(-1) - f(-4)]/[ -1+4 ]
[ f(-1) - f(-4)]/[ 3 ]
which is why the answer is choice C for the first blank

-------------------------------------------

To compute the value of f(-1), we draw a vertical line through -1 on the x axis. This vertical line crosses the diagonal function graph at the point (-1,3). The y value of this point is what we want. Plugging in x = -1 leads to y = 3. This is why f(-1) = 3
If you want, you can draw a horizontal line through (-1,3) and you'll see it touching 3 on the y axis.

-------------------------------------------

Follow similar steps as above to compute f(-4). Draw a vertical line through x = -4 on the x axis. Mark the point where the vertical line crosses the diagonal line. This point is (-4,-3). Optionally draw a horizontal line over til you hit the y axis and you'll find that y = -3 corresponds to x = -4

This is why f(-4) = -3

-------------------------------------------

We'll use the last three sections to compute the average rate of change. Everything combines together building up to this moment.

From the first part, we had the formula
[ f(b) - f(a) ]/[ b - a ]
[ f(-1) - f(-4)]/[ 3 ]

We can replace the "f(-1)" with 3 since we found that f(-1) = 3
Similarly, f(-4) = -3 so we can replace the "f(-4)" with -3

Doing those replacements and simplifying leads to...

[ f(-1) - f(-4)]/[ 3 ]
[ 3 - (-3)]/[ 3 ]
[ 3 + 3]/[ 3 ]
6/3
2

So the average rate of change is 2

Note: because the entire graph is a straight line, the average rate of change for any interval a < x < b is going to be equal to the slope m. In this case, the slope of the line is m = 2/1 = 2. We move up 2 units each time we move to the right 1 unit along the diagonal line.

6 0
3 years ago
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