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olga nikolaevna [1]

3 years ago

13

-8 + (-4) please help me find the answer 20 pts

2 answers:

Masteriza [31]3 years ago

8 0

A negative plus a negative make a negative because your just adding to the negative side of the number line. -8+-4=-12 ANSWER:-12

cestrela7 [59]3 years ago

7 0

-12 because -8+(-4) = -8 - 4= -12.

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A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wave

erma4kov [3.2K]

Answer:

A Pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm and 96 cm but does not resonate at any wavelengths longer than these. This pipe is:

A. closed at both ends

B. open at one end and closed at one end

C. open at both ends.

D. we cannot tell because we do not know the frequency of the sound.

The right choice is:

B. open at one end and closed at one end .

Step-by-step explanation:

Given:

Length of the pipe, $L$ = 120 cm

Its wavelength $\lambda_1$ = 480 cm

$\lambda_2$ = 160 cm and $\lambda_3$ = 96 cm

We have to find whether the pipe is open,closed or open-closed or none.

Note:

The fundamental wavelength of a pipe which is open at both ends is 2L.
The fundamental wavelength of a pipe which is closed at one end and open at another end is 4L.

So,

The fundamental wavelength:

⇒ $4L=4(120)=480\ cm$

It seems that the pipe is open at one end and closed at one end.

Now lets check with the subsequent wavelengths.

For one side open and one side closed pipe:

An odd-integer number of quarter wavelength have to fit into the tube of length L.

⇒ $\lambda_2=\frac{4L}{3}$ ⇒ $\lambda_3=\frac{4L}{5}$

⇒ $\lambda_2=\frac{4(120)}{3}$ ⇒ $\lambda_3=\frac{4(120)}{5}$

⇒ $\lambda_2=\frac{480}{3}$ ⇒ $\lambda_3=\frac{480}{5}$

⇒ $\lambda_2=160\ cm$ ⇒ $\lambda_3=96\ cm$

So the pipe is open at one end and closed at one end .

6 0

3 years ago

Write the percent as a fraction 77.5%

zysi [14]

77.5%

Change to decimal:-

77.5 ÷ 100 = 0.775

775/1000

31/40

77.5% = 31/40

6 0

3 years ago

A foreman for an injection-molding firm admits that on 55% of his shifts, he forgets to shut off the injection machine on his li

motikmotik

Answer:

0.8594

Step-by-step explanation:

Let a denote the event of forgetting to shut off machine and b be the event of being defective.

-A foreman forgets to shut off machine 55% of the time.

-If he forgets, 15% of molds are defective.

-If he does not, 3% of molds are defective.

#The probability that he forgot to shut off the machine is calculated as:

$P(a \ and \ b)=0.55\times 0.15\\\\=0.0825\\\\$

P(a and ~b)=0.55(1-0.15)=0.4675

P(~a and b) = (1-0.55)*0.03=0.0135

P(~a and ~b) = (1-0.55)*(1-0.03)=0.4365

#Conditional probability is defined as:

$P(a|b)=\frac{P(a \ and\ b)}{P(a)}\\\\=\frac{P(a \ and \ b)}{[(P(a \ and \ b)+P(\~a \ and \ b)}\\\\\\=\frac{0.0825}{0.0825+0.0135}\\\\\\=0.8594$

Hence, the probability that the foreman forgot to shut off the machine the previous night is 0.8594

5 0

3 years ago

Note: Enter your answer and show all the steps that you use to solve this problem in the space provided.

nikitadnepr [17]

Answer:

The answer should be 45

Step-by-step explanation:

To get the whole are you would have to multiply the lenght with the Width and then take that answer and multiply it with the height

<u>BUT</u>

because you want the surface area, it would be just the lenght and width

15x3=45

so 45 is your answer.

7 0

3 years ago

HELPPPP!!! TRUE OR FALSE

shusha [124]

I think it may be true, please correct me if i am wrong

3 0

3 years ago

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