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dlinn [17]
3 years ago
10

He loudness of a pile driver is 112 dB. About how many times the sound intensity of the jackhammer is the sound intensity of a p

ile driver? Round to the nearest ten.
Mathematics
2 answers:
andrey2020 [161]3 years ago
5 0

Answer:

40

Step-by-step explanation:

Edge 2020

chubhunter [2.5K]3 years ago
3 0

Complete question :

The loudness of a jack hammer is 96 dB. Its sound intensity is about 0.004.

The loudness of a compactor is 94 dB. Its sound intensity is about 0.0025.

The sound intensity of the jack hammer is about 1.6 times the sound intensity of the compactor.

The loudness of a pile driver is 112 dB. About how many times the sound intensity of the jackhammer is the sound intensity of a pile driver? Round to the nearest ten.

Answer:

40

Step-by-step explanation:

Given that:

Sound intensity of jackhammer = 0.004

Sound intensity of compactor = 0.0025

Sound intensity of jackhammer is about 1.6 times the sound intensity of a compactor

Each factor of 10 in intensity corresponds to 10dB

Pile driver with loudness of 112dB ; 112 / 10 = 11.2

Hence, 10^11.2 = 1.58489 * 10^11

Hence, sound intensity (I) in watts per m²

I = 1.58489 * 10^11 * 10^-12

I = 1.58489 * 10-1

I = 0.158489

Comparing the intensity of pile driver and jackhammer :

Intensity of piledriver / Intensity of jackhammer

0.158489 / 0.004

= 39.622

= 40 (nearest ten)

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Assume the population has a normal distribution. A sample of 25 randomly selected students Has a mean test score of 81.5 With a
Natasha_Volkova [10]

Answer:

The 90% confidence interval for the mean test score is between 77.29 and 85.71.

Step-by-step explanation:

We have the standard deviation for the sample, so we use the t-distribution to solve this question.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 25 - 1 = 24

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 24 degrees of freedom(y-axis) and a confidence level of 1 - \frac{1 - 0.9}{2} = 0.95. So we have T = 2.064

The margin of error is:

M = T\frac{s}{\sqrt{n}} = 2.064\frac{10.2}{\sqrt{25}} = 4.21

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 81.5 - 4.21 = 77.29

The upper end of the interval is the sample mean added to M. So it is 81.5 + 4.21 = 85.71.

The 90% confidence interval for the mean test score is between 77.29 and 85.71.

6 0
3 years ago
Your school is planning a field trip to the zoo. There are two different bus companies that the school can use.
8090 [49]

Answer:

4 students can go to the first one then 2 students can go the second bus

Step-by-step explanation:

$39×4= 156

$79×2=158

5 0
3 years ago
Find the general solution of {y}''-3y=8e^{3t}+4sin(t) .
babunello [35]

Answer:

y(x)=C_1e^{\sqrt3t}+C_2e^{-\sqrt3t}-\frac{4}{3}e^{3t}-sint

Step-by-step explanation:

We are given that linear differential equation

y''-3y=8e^{3t}+4 sint

Auxillary equation

D^2-3=0

D=\pm \sqrt3

C.F=C_1e^{\sqrt3t}+C_2e^{-\sqrt3}

P.I=\frac{8e^{3t}+4sin t}{D^2-3}

P.I=\frac{8e^{3t}}{9-3}+4\frac{sint }{-1-3}

P.I=e^{ax}{\phi (D+a)} and P.I=\frac{sinax}{(\phi D)}where D square is replace by - a square

P.I=-\frac{4}{3}e^{3t}- sint

Hence, the general solution

G.S=C.F+P.I

y(x)=C_1e^{\sqrt3t}+C_2e^{-\sqrt3t}-\frac{4}{3}e^{3t}-sint

3 0
3 years ago
Lindsey was making got chocolate. She used 3 cups of water to 2 tsp of coco mix. What is the ratio of coco mix to the water?​
sineoko [7]

Answer:

Ratio of coco mix to water is 2 : 3.

Step-by-step explanation:

Given that:

Lindsey used 3 cups of water to 2 tsp of coco mix to make chocolate.

Ratio is the quantitative relationship between two amounts.

Ratio of coco mix to water.

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3 0
2 years ago
The length and width of a rectangle are shown below.
natulia [17]

Answer:

-2x² + 90x + 500

Step-by-step explanation:

Use FOIL method

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                             = 50*(2x) + 50*10 + (-x)*2x + (-x)*10

                             = 100x + 500 - 2x² - 10x

                             = -2x² + 10<u>0x - 10x </u>+ 500  {Combine like terms}

                            = -2x² + 90x + 500

7 0
3 years ago
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