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3 years ago

Solve using elimination. 4x − 7y = 19 5x − 7y = 15

Mathematics

1 answer:

Likurg_2 [28]3 years ago

8 0

Answer:

Point Form: (-4, -5)

Equation Form: x = -4, y = -5

Step-by-step explanation:

Add the equations in order to solve for the first variable. Plug this value into the other equations in order to solve for the remaining variables.

Brainliest Please!!!!!

- Hermionia

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You select a random sample of n=14 families in your neighborhood and find the following family sizes (number of people in the fa

satela [25.4K]

Answer:

a. Best estimate for the mean family size for the population of all families in a country is 16.3571428571

b. 95% confidence interval for the estimate is 16.3571428571±0.7106240840. That is between 15.6465187731 and 17.0677669411

c. The sample is unlikely to be very representative of all families in a country.

Step-by-step explanation:

a. mean family size for the population of all families in a country can be estimated as sample mean, and calculated as:

$\frac{15+ 16+ 19+ 18+ 17+ 15+ 16+ 16+ 15+ 16+ 15+ 16+ 17+ 18 }{14}$ ≈ 16.3571428571

b. 95% confidence interval for the estimate can be calculated using the equation CI=M± $\frac{t*s}{\sqrt{N} }$ where

M is the mean estimate (16.3571428571)

t is the corresponding statistic in the 95% confidence level and with 14 degrees of freedom (2.160)

s is the standard deviation of the sample (1.2309777100)

N is the sample size (14)

s can be calculated as square root of mean squared differences from the sample mean.

Thus 95% CI=16.3571428571± $\frac{2.160*1.2309777100}{\sqrt{14} }$ ≈ 16.3571428571±0.7106240840

The sample is unlikely to be very representative of all families in a country because as the sample data increases, estimate will improve.

7 0

3 years ago

Read 2 more answers

What is the median of these scores, 98,82,100,84?

Lerok [7]

Answer:

Hello! The median is 82 and 100.

Step-by-step explanation:

The median is just the number or numbers in the middle! Hope this helps!

5 0

3 years ago

Read 2 more answers

Use the equation below to calculate the average speed for each problem, then complete the data table below. Problem Distance Tim

Naddik [55]

1. Answer is 4.5 km / hr.

... because you divide the time but the distance so for this question you divide 22.5 by 5 and that's your answer. do the same for every question! hope this helps.

4 0

3 years ago

A contractor needs to put a carpet in the hallway of a house, the diagram of the houses is below.All of the sides of the figure

Vera_Pavlovna [14]

Break it into squared and rectangles and find the area of those first then add it all together

For your square you would get 16 ft squared

For your rectangle you would get 32 ft squared

For your other rectangle you would get 32 ft squared as well

Then add those all together to get the full answer

80 ft squared

Hope this helps :)

5 0

4 years ago

A boat traveled 147 miles downstream and back. The trip downstream took 7 hours. The trip back took 21 hours. What is the speed

zimovet [89]

Answer:

The speed of current is 7 miles per hour

Step-by-step explanation:

Given as :

The distance cover by boat in downstream = D = 147 miles

The distance cover by boat in upstream = d = 147 miles

The time taken in downstream trip = T = 7 hours

The time taken in upstream trip = t = 21 hours

Let The speed of boat in still water = x mi/h

And The speed of current = y mi/h

The speed in downstream = S = (x + y) mi/h

The speed in upstream = s = (x - y) mi/h

Now, According to question

∵ Distance = speed × time

For downstream

D = S × T

Or, 147 miles = (x + y) mi/h × 7 hours

i.e 7 (x + y) = 147

Or, x + y = $\dfrac{147}{7}$

∴ x + y = 21 ........A

For upstream

d = s × t

Or, 147 miles = (x - y) mi/h × 21 hours

i.e 21 (x - y) = 147

Or, x - y = $\dfrac{147}{21}$

∴ x - y = 7 .......B

Now, Solving equations A and B

So, (x + y) + (x - y) = 21 + 7

Or, (x + x) + (y - y) = 28

Or, 2 x + 0 = 28

∴ x = $\dfrac{28}{2}$

i.e x = 14 miles per hour

The speed of boat in still water = x = 14 mi/h

Now, putting the value of x into eq B

So, y = x - 7

Or, y = 14 - 7

i.e y = 7 miles per hour

The speed of current = y = 7 mi/h

Hence, The speed of current is 7 miles per hour . Answer

7 0

3 years ago