Density practice

Identify the vertex, focus, and directrix. y=1/8y^2

Brut [27]

If all the equations for the directrix are "x = " lines then this is a y^2 parabola. The actual equation is $x= \frac{1}{8}y^2$ . The standard form for a positive sideways-opening parabola is $(y-k)^2=4p(x-h)$ . We know from the equation that the vertex of the parabola is at the origin, or else the translation would be reflected within the parenthesis in the equation. Our equation has no parenthesis to indicate movement from the origin. The vertex is (0, 0). Got that out of the way. That simplifies our standard form down to $y^2=4p(x)$ . Let's take a look at our equation now. It is $x= \frac{1}{8}y^2$ . We could rewrite it and make it a closer match to the standard form if we multiply both sides by 8 to get rid of the fraction. That gives us an equation that looks like this: $y^2=8x$ . That means that 4p = 8, and p = 2. p is the distance that the focus and the directrix are from the vertex. Since this is a positive parabola, it opens up to the right. Which means, then, that the focus is to the right of the vertex, 2 units to be exact, and the directrix is 2 units to the left of the vertex. The formula for the focus is (h + p, k). Our h is 0, our k is 0 and our p is 2, so the coordinates of the focus are (2, 0). Going 2 units to the left of the origin then puts our directrix at the line x = -2. Your choice then as your answer is b.

6 0

3 years ago

Forty-seven percent of fish in a river are catfish. Imagine scooping out a simple random sample of 25 fish from the river and ob

Alexxx [7]

Question options:

The standard deviation is 0.0998. The 10% condition is not met because there are less than 250 fish in the river.

The standard deviation is 0.0998. The 10% condition is met because it is very likely there are more than 250 fish in the river.

The standard deviation is 0.9002. The 10% condition is met because it is very likely there are more than 250 fish in the river.

The standard deviation is 0.9002. The 10% condition is not met because there are less than 250 fish in the river.

We are unable to determine the standard deviation because we do not know the sample mean. The 10% condition is met because it is very likely there are more than 250 fish in the river

Answer:

The standard deviation is 0.0998. The 10% condition is met because it is very likely there are more than 250 fish in the river

Explanation:

Formula to calculate standard deviation = √p(1-p)/n

Given p= population proportion

n= sample size

From the question,

We are given p(population proportion of catfish in the river)= 0.47

n(sample size of fish collected from river) = 25

The standard deviation using the formula above = √0.47(1-0.47)/25

= 0.0998

The 10% condition demands that a sample size be not less than 10% of the population

To check if the 10% condition was met, we know that a river will likely have up to 250 fish in it and so,

10% of 250= 0.10×250=25 fish

Therefore the option B chosen is correct

8 0

3 years ago

20 POINTS Compost costs $10 per cubic yard and topsoil costs $2 per cubic yard. Maria needs more than 10 cubic feet of topsoil.

Morgarella [4.7K]

I can't see the graph but let's use logic
hmm, more than 10 cubic feet of topsoil so the first and 2nd options are wrong

let's ee the costs
3rd option
10*1=10
2*12=24
10+24=34 and 34<50, that is fine

4th option
3*10=30
2*12=24
30+24=54
54>50, nope, that is over cost

answer is 3rd one
the one with 1 cubic yard compost and 12 cubic yard topsoil

8 0

3 years ago

Read 2 more answers

Please help me I appreciate

alex41 [277]

Think your answer would be C or D.
it's your choice to decide between those two now.

8 0

3 years ago

Based on the data which company most likely has the longest average commute time per employee?

Natalija [7]

Company 1 average= 24.4 minutes
company 2 average= 19.8 minutes
company 3 average= 15 minutes
company 4 average= 19 minutes

The answer is 24.4 or company one

3 0

3 years ago