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3 years ago

Help me answer question 8a and b, and I’ll give u 10 points lol

Mathematics

1 answer:

iren [92.7K]3 years ago

3 0

Answer:

Step-by-step explanation:

Find h when v = 20 and r = 3

Putting values in the formula

20 = (3.14)(3)2h

20 = (3.14)(9)h

20 = 28.26h

20/28.26 = h

R when v = 100 and h = 5

100 = (3.14)r2(5)

100/5 = 3.14r2

20 = 3.14r2

20/3.14 = r2

6.36 = r2

Square root on both sides

2.52 = r

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Calculate the surface area of the closed half-cylinder. all measurements are in cm<br>

AVprozaik [17]

Answer:

2656.31 $cm^{2}$

Step-by-step explanation:

To calculate the surface area, we need to find the area of all the faces, and add them together.

The faces of the cylinder are: the rectangular base, the curved top, and the two semicircles on the side.

Rectangular base:

A = length x width

A = 29.3 x 16.2

A = 474.66

Two semicircles:

A = $\pi$ x $radius^{2}$ (I'm using the formula for a circle, because the two semicircles are identical, so together they form a circle)

radius = 29.3/2 = 14.65

A = $\pi$ x $14.65^{2}$

A = 674.256 (rounded to 3 decimal places)

Curved top:

The curved top, when flattened out, becomes a rectangle with a length of 16.2. The width is equal to half the circumference of the circle formed by the two semicircles.

To find the width, use the circumference (C) formula.

C = $\pi$ x diameter

diameter = 29.3

C = $\pi$ x 29.3

C = 93.049 (rounded to 3 DP)

Area (of curved top) = length x width

A = 16.2 x 93.049

A = 1507.394 (rounded to 3 DP)

Surface Area

SA = 474.66 + 674.256 + 1507.394

SA = 2656.31 $cm^{2}$

8 0

3 years ago

Mr. Hamilton has 60,000 to invest in a tax-free fund and in a money market fund. The tax-free fund pays 7.5%, and the money mark

Valentin [98]

Answer:

He should invest $31,000 in tax-free to get a return of $4,790

Step-by-step explanation:

Let the amount he will invest in tax-free be $x while the amount in money market be $y

Adding both we have the total;

x + y = 60,000 ••••••••(i)

Then let’s work with the percentages;

7.5% of x + 8.5% of y = 4,790

7.5/100 * x + 8.5/100 * y = 4,790

7.5x/100 + 8.5y/100 = 4790

multiply through by 100

7.5x + 8.5y = 479000 ••••••(ii)

From i, y = 60,000 - x

Put this into ii

7.5x + 8.5(60,000-x) = 479000

7.5x + 510,000 -8.5x = 479000

8.5x - 7.5x = 510,000 - 479,000

x = $31,000

6 0

3 years ago

And plz show an example.

andrey2020 [161]

First question: x= 1 2/3 + y
y= -1 2/3 - x
second question: y= 6 - 7x
x= y + 6/7

5 0

3 years ago

Solve the equation -12 = f/0.2 (Thats a fraction)

Shalnov [3]

-12 = f/0.2

First, we can start out by making our goal to get the variable (f) on one side of the problem by itself. To do this, multiply both sides by 0.2.
$-12 \times 0.2 = f$

Second, our next step is to multiply -12 times 0.2. This can be solved in your head, on a piece of paper, on a calculator, etc. (-12 times 0.2 = 2.4).
$-2.4 = f$

Third, our last step will be to switch sides. Basically flip the problem.
$f = -2.4$

Answer: $\fbox {x = -2.4}$

8 0

4 years ago

Write this fraction in index form

expeople1 [14]

Answer:

$7^{-1/5}$

Step-by-step explanation:

$\frac{1}{\sqrt[5]{7}}=\frac{1}{7^{1/5}}=7^{-1/5}$

6 0

1 year ago