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3 years ago

10

A circle passes through point (-2, -1) and its center is at (2, -1). Which equation represents the circle?

1 answer:

Anastaziya [24]3 years ago

7 0

Answer:

$\text{A)}\qquad (x-2)^2+(y+1)^2=16$

Step-by-step explanation:

The formula for a circle of radius r centered at (h, k) is ...

(x -h)^2 +(y -k)^2 = r^2

Both of the given points are on the line y=-1. The distance between them is the difference of their x-coordinates, 2 -(-2) = 4. So, the radius of the circle is 4 and the equation becomes ...

(x -2)^2 +(y -(-1))^2 = 4^2

(x -2)^2 +(y +1)^2 = 16 . . . . . . . . . matches choice A

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The scores on an achievement test are normaly distributed with mean µ = 100 and standard deviation σ = 100. What should the scor

ser-zykov [4K]

Answer:

the student should score atleast 229 to be among the top 10%.

Step-by-step explanation:

in terms of the normal distribution, and if the table that you're using calculates the area of the normal distribution from the mean to a point x, only then what we are actually finding the value 'x' at which the z-score is at 40% (the rest 50% is already skipped by the table)

$P(0.4) = \dfrac{x - \mu}{\sigma}$

after finding the the value at this z-score, we can find the value of x at which the score is in the top 10% range.

we can find the z-score either using a normal distribution table or calculator. (but be sure what area is it calculating)

looking at the table the closest value we can find is, 0.4015 at z = 1.29 ((it is above 40% because we want to be in the top 10% range)

$P(0.4015) = \dfrac{x - 100}{100}$

$1.29 = \dfrac{x - 100}{100}$

$x = 1.29(100) + 100$

$x = 229$

the student should score atleast 229 to be among the top 10%.

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3 years ago

If 84 cookies will serve 24 students, how many cookies are needed for 30 students ?

allsm [11]

105 cookies
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P=45,000−1,000mspace, P, equals, 45, comma, 000, minus, 1, comma, 000, mPeople start to leave the stadium at the end of a footba

nexus9112 [7]

Answer:

45,000 people

Step-by-step explanation:

Let

P -----> the number of people, that are left in the stadium

M ----> the time in minutes

we have

$P=45,000-1,000M$

This is a linear equation in slope intercept form

where

The slope is

$m=-1,000\ \frac{people}{minute}$ ----> is negative because is a decreasing function

The P-intercept is

$b=45,000$

Remember that the P-intercept is the value of P when the value of M is equal to zero

That means

For M=0 min

P=45,000 people (number of people that were present when the game ended but before people started to leave)

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3 years ago