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3 years ago

What is the formula for the confidence interval? Then, define what each variable represents.

1 answer:

7 0

The confidence interval for a (1−α)% confidence level is given by

(θ0−Zα/2 σ/√n, θ0+Zα/2 σ/√n)

θ0 is the measured statistic, Zα/2 is the cutoff/critical value, and σ/√n is the standard error. σ is the population standard deviation (if known) or can be estimated by a sample standard deviation. n is the sample size. The cutoff value depends on the test you wish to use, and θ0 depends on the statistic you wish to estimate.

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Factor -7x3 + 21x2 + 3x - 9 by grouping. What is the resulting expression?

irga5000 [103]

Answer:

$(x-3)(-7x^2+3)$ is the resulting expression after grouping

Step-by-step explanation:

Given:

$-7x^3+21x^2+3x-9$

Now taking common $-7x^2$ from 1st 2 numbers and and 3 common from last we get

$-7x^2(x-3)+3(x-3)$

Now taking x-3 common from both numbers we get

$(x-3)(-7x^2+3)$ which is the final equation after grouping

8 0

3 years ago

Whats 3(x + 2) = 21? show work please !!

dybincka [34]

Answer:

x=5

Step-by-step explanation:

$3(x+2)=21$

$3x+6=21$

$3x+6-6=21-6\\\\3x=15\\\\\frac{3x}{3} = \frac{15}{3} \\\\x=5$

5 0

3 years ago

Read 2 more answers

Write 2.4 as a mixed number and as an improper fraction. Write your answers in simplest form.

Y_Kistochka [10]

Answer:

Step-by-step explanation:

24/10, 2 4/10 , 12/5

3 0

3 years ago

Avery can run at 10 uph. The bank of a river is represented by the line 4x + 3y = 12, and Avery is at (7, 5). How much time does

Reil [10]

The minimum distance will be along a perpendicular line to the river that passes through the point (7,5)

4x+3y=12

3y=-4x+12

y=-4x/3+12/3

So a line perpendicular to the bank will be:

y=3x/4+b, and we need it to pass through (7,5) so

5=3(7)/4+b

5=21/4+b

20/4-21/4=b

-1/4=b so the perpendicular line is:

y=3x/4-1/4

So now we want to know the point where this perpendicular line meets with the river bank. When it does y=y so we can say:

(3x-1)/4=(-4x+12)/3 cross multiply

3(3x-1)=4(-4x+12)

9x-3=-16x+48

25x=51

x=51/25

x=2.04

y=(3x-1)/4

y=(3*2.04-1)/4

y=1.28

So now that we know the point on the river that is closest to Avery we can calculate his distance from that point...

d^2=(x2-x1)^2+(y2-y1)^2

d^2=(7-2.04)^2+(5-1.28)^2

d^2=38.44

d=√38.44

d=6.2 units

Since he can run at 10 uph...

t=d/v

t=6.2/10

t=0.62 hours (37 min 12 sec)

So it will take him 0.62 hours or 37 minutes and 12 seconds for him to reach the river.

8 0

3 years ago

Question 1

yaroslaw [1]

Answer:

sorry but i need some points right now so just ignore this

Step-by-step explanation:

8 0

3 years ago