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sveticcg [70]
3 years ago
15

If y varies directly ás x, and y = 7 when x = 3. find y when x=7

Mathematics
1 answer:
vlada-n [284]3 years ago
5 0

Answer:

y = \frac{49}{3}

Step-by-step explanation:

Given y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition

x = 3 when y = 7

k = \frac{y}{x} = \frac{7}{3}, thus

y = \frac{7}{3} x ← equation of variation

When x = 7, then

y = \frac{7}{3} × 7 = \frac{49}{3}

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A school wants to have a metal gate placed around it. However they only want to cover three sides of the school and they only ha
Fofino [41]

Answer:

Width = 139.445 ft and Length = 1721.11 ft or

Width = 860.555 ft and Length = 278.89 ft

Step-by-step explanation:

If the school has a rectangular shape, we have that its perimeter and area are:

Perimeter = 2*Length + 2*Width

Area = Length * Width

If we just want to cover 3 sides of the school, we can affirm that:

2000 = Length + 2*Width (eq1)

And the area is 240,000 ft2, so:

240000 = Length * Width (eq2)

From (eq1), we have that:

Length = 2000 - 2*Width

Using this value in (eq2), we have:

240000 = (2000 - 2*Width) * Width

240000 = 2000*Width - 2*Width^2

Width^2 - 1000*Width + 120000 = 0

Using Bhaskara's formula, we have:

Delta = 1000^2 - 120000*4 = 520000

sqrt(Delta) = 721.11

Width1 = (1000 + 721.11)/2 = 860.555 ft

Width2 = (1000 - 721.11)/2 = 139.445 ft

If we use Width = 139.445 ft, we will find Length = 1721.11 ft

If we use Width = 860.555 ft, we will find Length = 278.89 ft

Both pairs of dimensions are valid answers, as they would use 2000 feet of gate and the area of the school would be 240,000 ft2

3 0
3 years ago
A calculus student takes a 20-question, multiple choice test with 5 answer choices for each question. find the mean and standard
mario62 [17]
Suppose the student guesses the answers, we shall consider this a binomial probability problem of success. This implies that getting a question right is p=1/5.
The number of questions is n=20 questions.
The mean of binomial distribution is 
mean=n*p= 20*1/5=4

b] The standard deviation of a binomial distribution is given by:
σ=√(n*p*(1-p))
=√(20*0.2*0.8)
=1.79~1.8

Answer:
μ=4 ; σ=1.8
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4 years ago
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Sonbull [250]

Answer:

Step-by-step explanation:

6 0
3 years ago
On a standardized exam, the scores are normally distributed with a mean of 79 and a standard deviation of 20. Find the z-score o
Anit [1.1K]

Answer:

z = 2.1

Step-by-step explanation:

z=\frac{x-\mu}{\sigma}\\ \\z=\frac{121-79}{20}\\ \\z=\frac{42}{20}\\ \\z=2.1

This tells us that the person's score of 121 places them 2.1 standard deviations above the mean score of 79.

3 0
3 years ago
How do you get 24 out of the numbers 9 8 5
iris [78.8K]

Answer:

Even if the numbers can be used more than once, this is still no solutions sice all answers will get you to 22 instead of 24.

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