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-BARSIC- [3]
3 years ago
11

Selma hypothesizes that the mass of a sample of water will not change if it is frozen. She conducts an experiment to test her hy

pothesis. Her experimental steps are as follows:
1. Fill a beaker with 500 mL of water.
2.
3. Place the beaker in the freezer.
4. After the water freezes, place the beaker on the balance and measure its mass.

Which of the following steps is missing from Selma's experiment?

Place the beaker on the balance and measure its mass.
Run the water through a filter to make sure there are no impurities in it.
Set a timer for 2 hours.
Use a thermometer to measure the water's temperature.
Mathematics
2 answers:
egoroff_w [7]3 years ago
4 0
Place a beaker on a balance and measure the mass
Sphinxa [80]3 years ago
4 0

Answer:

place the beaker on the balance and measure its mass.

Step-by-step explanation:

In order to see if the mass of the water changed, Selma first needs to find out what the mass of the liquid water is in order to compare it to the mass of the frozen water.

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Really need help on #15 please.
ollegr [7]

Step-by-step explanation:

Let's call L the length and W the width.  The length is 10 feet longer than the width, so:

L = W + 10

The area is the length times width, so:

119 = LW

Substituting:

119 = (W + 10) W

119 = W² + 10W

0 = W² + 10W − 119

0 = (W + 17) (W − 7)

W = -17 or 7

Since W must be positive, W = 7.

L = W + 10

L = 17

The length and width are 17 feet and 7 feet, respectively.

5 0
3 years ago
If you are offered one slice from a round pizza (in other words, a sector of a circle) and the slice must have a perimeter of 24
VARVARA [1.3K]

Answer:

A 12 in diameter will reward you with the largest slice of pizza.

Step-by-step explanation:

Let r be the radius and \theta be the angle of a circle.

According with the graph, the area of the sector is given by

A=\frac{1}{2}r^2\theta

The arc lenght of a circle with radius r and angle \theta is r \theta

The perimeter of the pizza slice is composed of two straight pieces, each of length r inches, and an arc of the circle which you know has length s = rθ inches. Thus the perimeter has length

2r+r\theta=24 \:in

We need to express the area as a function of one variable, to do this we use the above equation and we solve for \theta

2r+r\theta=24\\r\theta=24-2r\\\theta=\frac{24-2r}{r}

Next, we substitute this equation into the area equation

A=\frac{1}{2}r^2(\frac{24-2r}{r})\\A=\frac{1}{2}r(24-2r)\\A=12r-r^2

The domain of the area is

0

To find the diameter of pizza that will reward you with the largest slice you need to find the derivative of the area and set it equal to zero to find the critical points.

\frac{d}{dr} A=\frac{d}{dr}(12r-r^2)\\A'(r)=\frac{d}{dr}(12r)-\frac{d}{dr}(r^2)\\A'(r)=12-2r

12-2r=0\\-2r=-12\\\frac{-2r}{-2}=\frac{-12}{-2}\\r=6

To check if r=6 is a maximum we use the Second Derivative test

if f'(c)=0 and f''(c), then f(x) has a local maximum at x = c.

The second derivative is

\frac{d}{dr} A'(r)=\frac{d}{dr} (12-2r)\\A''(r)=-2

Because A''(r)=-2 the largest slice is when r = 6 in.

The diameter of the pizza is given by

D=2r=2\cdot 6=12 \:in

A 12 in diameter will reward you with the largest slice of pizza.

3 0
3 years ago
What two integers is 87 between
Alexxx [7]
the two integers 87 between is 86 87 89
7 0
3 years ago
if y varies inversely as x and y = 194 when x = -13, find y when x = 50. Round your answer to the nearest hundredth, if necessar
pashok25 [27]

Step-by-step explanation:

Since, y varies inversely as x.

\therefore \: y =  \frac{k}{x}  \\ (k = constant \: of \: proportionality) \\   \therefore \: xy =  k...(1) \\ plug \: y = 194 \:  \: and \:  \: x =  - 13 \: in \: (1) \\ \therefore \:  - 13 \times 194=  k \\ \therefore \: k =  - 2522 \\ substituting \: k =  - 2522 \: in \: (1) \\ xy =  - 2522...(2) \\ this \: is \: equation \: of \: variation. \\ plug \: x = 50 \: in \: (2) \\ 50 \times y =  - 2522 \\  \therefore \:y =  \frac{ - 2522}{50}  \\   \huge \red{ \boxed{\therefore \:y =   - 50.44}}

8 0
3 years ago
Mr.Silva needs to order pizza for 30 students.Each student should get 1/4 of a pizza.How many pizzas should Mr Silva order?How m
zimovet [89]
The answer is he needs 7.5 pizzas but you can’t do that so you round up to 8 pizzas
3 0
3 years ago
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