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3 years ago

Solve the system for x and y -3x+8y=103 -5x-8y=-255

Mathematics

1 answer:

Romashka-Z-Leto [24]3 years ago

3 0

9514 1404 393

Answer:

(x, y) = (19, 20)

Step-by-step explanation:

The coefficients of y are opposites, so we can add the two equations to eliminate y.

(-3x +8y) +(-5x -8y) = (103) +(-255)

-8x = -152

x = 19 . . . . . . . divide by -8

Substituting into the first equation, we have ...

-3(19) +8y = 103

8y = 160

y = 20

The solution is (x, y) = (19, 20).

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Two opposing opinions were shown to a random sample of 1,500 buyers of a particular political news app in the United States. The

kifflom [539]

Answer:

A) 98% Confidence interval for the proportion of all US buyers of this particular app who would have chosen Opinion B

= (0.51, 0.57)

This means that the true proportion of all thay would chose opinion B can take on values between the range of (0.51, 0.57)

B) For the confidence interval obtained to be valid, the conditions stated must be satisfied and for the sampling distribution to be approximately normal, the number of buyers that chose Opinion B and the number of buyers that did not choose Opinion B must both be greater than 10.

Step-by-step explanation:

Confidence Interval for the population proportion is basically an interval of range of values where the true population proportion can be found with a certain level of confidence.

Mathematically,

Confidence Interval = (Sample proportion) ± (Margin of error)

Sample proportion of all US buyers of this particular app who would have chosen Opinion B = 0.54

Margin of Error is the width of the confidence interval about the mean.

It is given mathematically as,

Margin of Error = (Critical value) × (standard Error)

Critical value at 98% confidence interval for sample size of 1500 is obtained from the z-tables.

Critical value = 2.33

Standard error = σₓ = √[p(1-p)/n]

p = sample proportion = 0.54

n = sample size = 1500

σₓ = √(0.54×0.46/1500) = 0.0128685664 = 0.01287

98% Confidence Interval = (Sample proportion) ± [(Critical value) × (standard Error)]

CI = 0.54 ± (2.33 × 0.01287)

CI = 0.54 ± 0.02998)

98% CI = (0.51, 0.57)

98% Confidence interval = (0.51, 0.57)

B) The number of buyers that chose Opinion B and the number of buyers that did not choose Opinion B are both greater than 10. Why must this inference condition be met?

For this confidence interval to be obtained using sample data, a couple of conditions are necessary to be satisfied. They include;

- The sample data must have been obtained using a random sampling technique.

- The sampling distribution must be normal or approximately normal.

- The variables of the sample data must be independent of each other.

On the second point, the condition for a binomial distribution to approximate a normal distribution is that

np ≥ 10

and n(1-p) ≥ 10

The quantity np is the actual sample mean which is the actual number of buyers that chose Opinion B while n(1-p) is the number of buyers that did not chose Opinion B.

For the confidence interval obtained to be valid, the conditions stated must be satisfied and for the sampling distribution to be approximately normal, the number of buyers that chose Opinion B and the number of buyers that did not choose Opinion B must both be greater than 10.

Hope this Helps!!!

8 0

3 years ago

A farmer has 160 bushels of apple to sell at his roadside stand. He sells an average of

Damm [24]

Answer:

He sold 87-3/5 bushels in 6 days , he has 72-2/5 bushels left

Step-by-step explanation:

14-3/5 x 6 = Bushels sold in 6 days

6 0

3 years ago

Find the missing length of the triangle. Round to the nearest tenth. a = _____, b = 7, c = 9

kogti [31]

Answer: Maybe 5.7

Step-by-step explanation: To solve this we are going to need to understand the pythagorean theorem. we can use it as a way to find this certain side. if we put these numbers in the theorem, we get a^2+49=81 (7^2=49 and 9^2=81), we can subtract 49 on both sides and get 32. We would also need to take out the power of 2 on the side of the a^2, so you would do the square root of a^2, which would just become a and the square root of 32, which if you crunch the numbers on a calculator. You would get 5.656..... then you round it to the nearest tenth and get 5.7.

5 0

3 years ago

Read 2 more answers

How do I get help on my homework with this app

rosijanka [135]

Answer:

You post your questions

Step-by-step explanation:

Use the search button

6 0

3 years ago

Read 2 more answers

Which values are in the solution set of the compound inequality? Check all that apply. 4(x + 3) ≤ 0 or x + 1 > 3 –6 –3 0 3 8

Colt1911 [192]

we have

$4(x + 3) \leq 0$ -------> inequality 1

$x + 1 > 3$ -------> inequality 2

we know that

In this system of inequalities, for a value to be the solution of the system, it is enough that it satisfies at least one of the two inequalities.

let's check each of the values

case 1) x=-6

Substitute the value of x=-6 in the inequality 1

$4(-6 + 3) \leq 0$

$4(-3) \leq 0$

$-12 \leq 0$ -------> is ok

The value of x=-6 is a solution of the compound inequality-----> It is not necessary to check the second inequality, because the first one satisfies

case 2) x=-3

Substitute the value of x=-3 in the inequality 1

$4(-3 + 3) \leq 0$

$4(0) \leq 0$

$0 \leq 0$ -------> is ok

The value of x=-3 is a solution of the compound inequality-----> It is not necessary to check the second inequality, because the first one satisfies

case 3) x=0

Substitute the value of x=0 in the inequality 1

$4(0 + 3) \leq 0$