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icang [17]
3 years ago
15

A train is moving at an average speed of 180 m/s. how long will it take to reach the station. Both stations are 80 km apart?

Mathematics
1 answer:
Alexxandr [17]3 years ago
4 0

1 km = 1000 meters.

Find total meters: 80 km x 1000 meters per km = 80,000 meters.

Divide total meters by the given speed:

80,000 meters / 180 m/s = 444.44 seconds.

1 minute = 60 seconds

444.44. Seconds / 60 seconds per minute = 7.41 minutes = 7 minutes 24.42 seconds

Total time = 7 minutes 24.42 seconds

Round as needed.

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A pew research Center project on the state of news media showed that the clearest pattern of news audience growth in 2012 came o
KengaRu [80]

Answer:

Step-by-step explanation:

Given that:

the sample proportion p = 0.39

sample size = 100

Then np = 39

Using normal approximation

The sampling distribution from the sample proportion is approximately normal.

Thus, mean \mu _{\hat p} = p = 0.39

The standard deviation;

\sigma = \sqrt{\dfrac{p(1-p)}{n} }

\sigma = \sqrt{\dfrac{0.39(1-0.39)}{100} }

\sigma = 0.048

The test statistics can be computed as:

Z = \dfrac{{\hat _{p}} - \mu_{_ {\hat p}} }{\sigma_{\hat p}}

Z = \dfrac{0.3 - 0.39 }{0.0488}

Z = -1. 8 4

From the z - tables;

P (\hat p \le 0.3 ) = P(z \le -1.84)

\mathbf{P (\hat p \le 0.3 ) = 0.0329}

(b)

Here;

the sample proportion = 0.39

the sample size n = 400

Since np = 400 * 0.39 = 156

Thus, using normal approximation.

From the sample proportion, the sampling distribution is approximate to the mean \mu_{\hat p} =  p = 0.39

the standard deviation \sigma_{\hat p} = \sqrt{\dfrac{p(1-p)}{n} }

\sigma_{\hat p} = \sqrt{\dfrac{0.39 (1-0.39)}{400} }

\sigma_{\hat p} =0.0244

The test statistics can be computed as:

Z = \dfrac{{\hat _{p}} - \mu_{_ {\hat p}} }{\sigma_{\hat p}}

Z = \dfrac{0.3 - 0.39 }{0.0244}

Z = -3.69

From the z - tables;

P (\hat p \le 0.3 ) = P(z \le -3.69)

\mathbf{P (\hat p \le 0.3 ) = 0.0001}

(c) The effect of the sample size on the sampling distribution is that:

As sample size builds up, the standard deviation of the sampling distribution decreases.

In addition to that, reduction in the standard deviation resulted in increases in the Z score, and the probability of having a sample proportion  that is less than 30% also decreases.

6 0
2 years ago
I NEED HELP ASAP PLZ!!!
polet [3.4K]

1. (7 , 0) and (11 , 3) → B and D

substitute each coordinate point into the left side of the equation and if equal to 21 then it is a solution.

( 7 , 0) → (3 × 7) - ( 4× 0)  = 21 - 0 = 21  

(11 , 3) → (3 × 11 )  - ( 4 × 3) = 33 - 12 = 21

2. ( 2 , - 9 ) is a solution to the equation

substitute the coordinates into the equation and if equal to 13 the it is the solution.

(2 , - 9 ) → (5 × 2 ) - (-9)/3 = 10 + 9/3 = 10 + 3 = 13

(3 , - 6) → (5 × 3) - (- 6)/3 = 15 + 6/3 = 15 + 2 = 17

thus (2 , -9 ) is the solution

4. x- intercept = (- 45 , 0)

to find the x- intercept let y = 0

1/3 x + 0 = - 15

1/3x = - 15

multiply both sides by 3

x = 3 × - 15 = - 45

thus x -intercept = ( - 45 , 0)



6 0
3 years ago
15 + r as a verbal expression
kodGreya [7K]

Hey there!

<h2>ANSWER: r+15</h2><h2>EXPLANATION:</h2><h2>15+r</h2>

Simplify by flipping.

r+15

Hope this helps!

- TestedHyperr

7 0
3 years ago
About how much difference in average leaf width would you find in two forests whose average annual rainfalls are near 1500 mm bu
goblinko [34]

Answer:

4.80 mm to 2 d.p

Step-by-step explanation:

w = f(r)

f'(r) = (dw/dr) = (0.0218 mm/mm)

So, for a small difference in rainfall of 220 mm, what is the corresponding small difference in width of leaves in the two forests given.

One definition of a derivative or a rate of change is that it is the ratio of very small differences in the dependent variable to very small differences in the independent variable.

Mathematically,

(dw/dr) = (Δw/Δr) for very small Δw and Δr.

0.0218 = (Δw/220)

Δw = 0.0218 × 220 = 4.796 mm = 4.80 mm to 2 d.p

Hope this Helps!!!

5 0
3 years ago
Are the answers correct or am I missing some?
AlekseyPX
Well,

Emily received $40.00 and then withdrew $40.00.  The final amount would be zero.

Jacoby climbed 782 feet to get to his campsite, and then descended 782 feet to get back to his car.  His final change is zero.

The Eagles mad two points, but then the Bulldogs evened it out with another two points.  The difference between the two scores would be the same.

Marcus ends up going down more than he goes up, so this is not a correct option.

The Ravens scored two points, but at the end the Raiders scored an additional 5 points, which set both teams to the same score.

Since there are an equal number of protons and electrons, and the protons have the same (but opposite) amount of charge as the electrons, the charges cancel each other out, leaving the atom with a neutral overall charge (0).
8 0
3 years ago
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