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Elan Coil [88]
3 years ago
9

Arithmetic Series Word Problems

Mathematics
1 answer:
MrRa [10]3 years ago
6 0

Answer:

$210 dollars

Step-by-step explanation:

we have to do 15 x12 first=180

plus 30=210

please tell me if this helped at all :)

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A plane takes off and flies at an angle of 11° with the ground. When it reaches an elevation of 500 ft, what is the distance flo
drek231 [11]

Answer:

It had flown 2620 ft along the diagonal.

Step-by-step explanation:

When the plane is taking off it forms we can form a triangle with it's height, horizontal distance and diagonal distance, which can be seen in the attached drawing. We can use the sine relation on the right triangle to determine "x", as shown below:

sin(11°) = 500/x

x*sin(11) = 500

x = 500/[sin(11)] = 2620 ft

It had flown 2620 ft along the diagonal.

7 0
3 years ago
A professor at a local community college noted that the grades of his students were normally distributed with a mean of 84 and a
creativ13 [48]

Answer:

A. P(x>91.71)=0.10, so the minimum grade is 91.71

B. P(x<72.24)=0.025 so the maximum grade could be 72.24

C. By rule of three, 200 students took the course

Step-by-step explanation:

The problem says that the grades are normally distributed with mean 84 and STD 6, and we are asked some probabilities. We can´t find those probabilities directly only knowing the mean and STD (In that distribution), At first we need to transfer our problem to a Standard Normal Distribution and there is where we find those probabilities. We can do this by a process called "normalize".

P(x<a) = P( (x-μ)/σ < (a-μ)/σ ) = P(z<b)

Where x,a are data from the original normal distribution, μ is the mean, σ is the STD and z,b are data in the Standard Normal Distribution.

There´s almost no tools to calculate probabilities in other normal distributions. My favorite tool to find probabilities in a Standard Normal Distribution is a chart (attached to this answer) that works like this:

P(x<c=a.bd)=(a.b , d)

Where "a.b" are the whole part and the first decimal of "c" and "d" the second decimal of "c", (a.b,d) are the coordinates of the result in the table, we will be using this to answer these questions. Notice the table only works with the probability under a value (P(z>b) is not directly shown by the chart)

A. We are asked for the minimum value needed to make an "A", in other words, which value "a" give us the following:

P(x>a)=0.10

Knowing that 10% of the students are above that grade "a"

What we are doing to solve it, as I said before, is to transfer information from a Standard Normal Distribution to the distribution we are talking about. We are going to look for a value "b" that gives us 0.10, and then we "normalize backwards".

P(x>b)=0.10

Thus the chart only works with probabilities UNDER a value, we need to use this property of probabilities to help us out:

P(x>b)=1 - P(x<b)=0.10

P(x<b)=0.9

And now, we are able to look "b" in the chart.

P(x<1.28)=0.8997

If we take b=1.285

P(x<1.285)≈0.9

Then

P(x>1.285)≈0.1

Now that we know the value that works in the Standard Normal Distribution, we "normalize backwards" as follows:

P(x<a) = P( (x-μ)/σ < (a-μ)/σ ) = P(z<b)

If we take b=(a+μ)/σ, then a=σb+μ.

a=6(1.285)+84

a=91.71

And because P(x<a)=P(z<b), we have P(x>a)=P(z>b), and our answer will be 91.71 because:

P(x>91.71) = 0.1

B. We use the same trick looking for a value in the Standard Normal Distribution that gives us the probability that we want and then we "normalize backwards"

The maximum score among the students who failed, would be the value that fills:

P(x<a)=0.025

because those who failed were the 2.5% and they were under the grade "a".

We look for a value that gives us:

P(z<b)=0.025 (in the Standard Normal Distribution)

P(z<-1.96)=0.025

And now, we do the same as before

a=bσ+μ

a=6(-1.96)+84

a=72.24

So, we conclude that the maximum grade is 72.24 because

P(x<72.24)=0.025

C. if 5 students did not pass the course, then (Total)2.5%=5

So we have:

2.5%⇒5

100%⇒?

?=5*100/2.5

?=200

There were 200 students taking that course

6 0
3 years ago
Find the slope of the line through the points (-4, 3) and (3, 5)
lukranit [14]
Use the formula y2 -y1/x2-x1
3 0
2 years ago
Read 2 more answers
Cheryl has $56 and wants to buy as many notebooks as she can to donate to her school. If each notebook costs $1.60, which inequa
natka813 [3]
The answer is B because n is equal to the number of notebooks. you can not exceed the amount of money that you have to buy the notebooks
8 0
3 years ago
Read 2 more answers
PLZ HELP FOR POINTS thank you
Liono4ka [1.6K]

Given : y = -25 and x = -5

We can notice that if we Multiply 'x' with 5 we get 'y'

That is (-5) × 5 = -25

⇒ x multiplied by 5 = y

(a) The Equation that relates x and y is 5x = y

(b) We found that the Equation of this Direct variation is : 5x = y

The Question is to find the value of y when x = 3

The Value of y at x = 3 can be found by simply substituting x = 3 in the equation we found.

⇒ y = 5x

⇒ y = 5 × 3

⇒ y = 15

So, the Value of y when x = 3 is 15

8 0
3 years ago
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