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777dan777 [17]
2 years ago
14

A study was designed to investigate the effects of two variables​(1) a​ student's level of mathematical anxiety and​ (2) teachin

g methodon a​ student's achievement in a mathematics course. Students who had a low level of mathematical anxiety were taught using the traditional expository method. These students obtained a mean score of 440 with a standard deviation of on a standardized test. Assuming no information concerning the shape of the distribution is​ known, what percentage of the students scored between 360 and 520 ​?
Mathematics
1 answer:
dimaraw [331]2 years ago
7 0

Using Chebyshev's Theorem, considering a standard deviation of 40, we have that at least 75% of the students scored between 360 and 520.

<h3>What does Chebyshev’s Theorem state?</h3>

When we have no information about the population distribution, Chebyshev's Theorem is used. It states that:

  • At least 75% of the measures are within 2 standard deviations of the mean.
  • At least 89% of the measures are within 3 standard deviations of the mean.
  • An in general terms, the percentage of measures within k standard deviations of the mean is given by 100(1 - \frac{1}{k^{2}}).

In this problem, considering a standard deviation of 40, we have that:

440 - 2 x 40 = 360.

440 + 2 x 30 = 520.

Within 2 standard deviations of the mean, no information about the distribution, hence, at least 75% of the students scored between 360 and 520.

More can be learned about Chebyshev's Theorem at brainly.com/question/25303620

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Write and solve the equations. A number y is five less than thirteen.
Genrish500 [490]

We can follow the following steps to make an equation and solve it.

Step 1:

five less than 13 means we have to subtract 5 from 13

so it becomes 13-5

Step 2:

A number y is five less than thirteen.

Now in algebraic expressions, "is" stands for "="

So we have:

y=13-5

Step 3:

Solving the equation to find y.

y=13-5

Subtracting 5 from 13, we get :

y=8

Answer:

For the given equation the solution is y=8.

4 0
3 years ago
Flying with the wind, a small plane flew 404 mi in 2 h. Flying against the wind, the plane could fly only 386 mi in the same amo
Alika [10]

Answer: rate of the plane is 197.5 mph

rate of wind is 4.5 mph

Step-by-step explanation:

Let x represent the rate of the plane in calm air.

Let y represent the rate of the wind.

Flying with the wind, a small plane flew 404 mi in 2 h. This means that the total speed with which the plane flew is (x + y) mph.

Distance = speed × time

Distance travelled by the plane while flying with the wind is

404 = 2(x + y)

Dividing both sides of the equation by 2, it becomes

202 = x + y- - - - - - - - - - - 1

Flying against the wind, the plane could fly only 386 mi in the same amount of time. This means that the total speed at which the plane flew is (x - y) mph.

Distance = speed × time

Distance travelled by the plane while flying against the wind is

386 = 2(x - y)

Dividing both sides of the equation by 2, it becomes

193 = x - y- - - - - - - - - - - 2

Adding equation 1 to equation 2, it becomes

395 = 2x

x = 395/2

x = 197.5

Substituting x = 197.5 into equation 1, it becomes

202 = 197.5 + y

y = 202 - 197.5

y = 4.5

3 0
3 years ago
When renting a limo for prom, the number of people varies inversely with the cost per person. Originally there were 4 people and
ioda

Answer:The new cost per person= $19 when there are 12 people

Step-by-step explanation:

Step 1

Let Number of people be rep as N

And Cost per person = C

such that the relationship of  number of people which varies inversely with the cost per person is given as

N∝ 1/C

Introducing constant of proportionality, k, we have that

N= K/C

such that when there were 4 people the cost per person was $57, K would be

N= K/C

4 = K /57

k= 57 X 4

k=228

Step 2

Therefore If the number of people changed to 12, cost per person would be

N= K/C

12= 228 / C

C= 228/12

C= 19

The new cost per person= $19 when there are 12 people

4 0
3 years ago
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pochemuha

Answer:

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3 years ago
Darren can get to work in 30 minutes. the speed limit is 35 mph, but there are three stop lights. with the traffic and lights, h
Radda [10]
To solve this problem you must apply the proccedure shown below:
 1. You have that Darren can get to work in 30 minutes and <span>with the traffic and lights, he can average </span>30 mph<span>.Therefore, you must apply the formula for calculate the distance, which is:
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 2. The time in hours is:
 </span>30 min=1/2 h&#10;<span>
 3. Substituying values, you have:
 </span>d=(30 mph)(1/2 h) \\ d=15 miles
<span> The answer is:</span>15 miles
3 0
3 years ago
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