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3 years ago

Helpppppppppppppppppppppppppppppppp[ppppppppp

Mathematics

1 answer:

rosijanka [135]3 years ago

4 0

-2.5>-1.5 because it’s the only one that makes sense (there’s a more logical explanation but i really don’t feel like explaining it unless you need me to :) )

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Chloe biked the same distance each day for 9 days. If she traveled 513 kilometers altogether, how many kilometers did she travel

kow [346]

Answer:

57 kilometers a day.

Step-by-step explanation:

I just divided 513 by 9 and got that.

5 0

3 years ago

Just do these two problems for me and I’ll be so happy

sveticcg [70]

5. y = x + 7
6. y = -x + 1

4 0

2 years ago

A tank contains 1600 L of pure water. Solution that contains 0.04 kg of sugar per liter enters the tank at the rate 2 L/min, and

goldfiish [28.3K]

Let S(t) denote the amount of sugar in the tank at time t. Sugar flows in at a rate of

(0.04 kg/L) * (2 L/min) = 0.08 kg/min = 8/100 kg/min

and flows out at a rate of

(S(t)/1600 kg/L) * (2 L/min) = S(t)/800 kg/min

Then the net flow rate is governed by the differential equation

$\dfrac{\mathrm dS(t)}{\mathrm dt}=\dfrac8{100}-\dfrac{S(t)}{800}$

Solve for S(t):

$\dfrac{\mathrm dS(t)}{\mathrm dt}+\dfrac{S(t)}{800}=\dfrac8{100}$

$e^{t/800}\dfrac{\mathrm dS(t)}{\mathrm dt}+\dfrac{e^{t/800}}{800}S(t)=\dfrac8{100}e^{t/800}$

The left side is the derivative of a product:

$\dfrac{\mathrm d}{\mathrm dt}\left[e^{t/800}S(t)\right]=\dfrac8{100}e^{t/800}$

Integrate both sides:

$e^{t/800}S(t)=\displaystyle\frac8{100}\int e^{t/800}\,\mathrm dt$

$e^{t/800}S(t)=64e^{t/800}+C$

$S(t)=64+Ce^{-t/800}$

There's no sugar in the water at the start, so (a) S(0) = 0, which gives

$0=64+C\impleis C=-64$

and so (b) the amount of sugar in the tank at time t is

$S(t)=64\left(1-e^{-t/800}\right)$

As $t\to\infty$ , the exponential term vanishes and (c) the tank will eventually contain 64 kg of sugar.

7 0

3 years ago

Which statements are true?

faust18 [17]

Question 3. The true statements are:
4g2 – g = g2(4 – g) ⇒ should be: 4g² - g = g(4g - 1)
9g3 + 12 = 3(3g3 + 4) ⇒ should be: 9g³ + 12 = 3(3g³ + 4) TRUE
24g4 + 18g2 = 6g2(4g2 + 3g) ⇒ should be: 24g⁴ + 18g² = 6g²(4g² + 3)
<span>35g5 – 25g2 = 5g2(7g3 – 5) </span>⇒ should be: 35g⁵ - 25g² = 5g²(7g³ - 5) TRUE

Question 4. Completely factored.
16y⁵ + 12y³ = 4y³(4y² + 3) FACTORED COMPLETELY
18y³ - 6y = 6y(3y² - 1)
20y⁷ + 10y² = 10y²(2y⁵ + 1)
32y¹⁰ - 24 = 8(4y¹⁰ - 3) FACTORED COMPLETELY

3 0

3 years ago

An environmental group conducted a study to determine whether crows in a certain region were ingesting food containing unhealthy

nydimaria [60]

Part A

Given info:

xbar = sample mean = 4.90 ppm
s = sample standard deviation = 1.12 ppm
n = 23 = sample size

Because n > 30 is not true, and we don't know the population standard deviation (sigma), this means we must use a T distribution.

The degrees of freedom here are n-1 = 23-1 = 22.

At 90% confidence and the degrees of freedom mentioned, the t critical value is roughly t = 1.717

Use a T distribution table or calculator to determine this. If you don't have a calculator for the task, then you can search out "inverse T calculator" and there are tons of free options to pick from.

The margin of error E is

E = t*s/sqrt(n)

E = 1.717*1.12/sqrt(23)

E = 0.400982

This is approximate and accurate to 6 decimal places.

The confidence interval is going to be xbar plus or minus that E value

L = lower bound = xbar - E = 4.90 - 0.400982 = 4.499018 = 4.50

U = upper bound = xbar + E = 4.90 + 0.400982 = 5.300982 = 5.30

The confidence interval in the format of (L, U) is (4.50, 5.30)

You could also express it as the format L < mu < U and it would be 4.50 < mu < 5.30; however, I'll stick to the first method.

<h3>Answer: (4.50, 5.30)</h3>

=====================================================

Part B

Since we know sigma = 2.6 is the population standard deviation, we can use a Z distribution now.

At 90% confidence, the z critical value is roughly 1.645; use a table or calculator to determine this.

$n = \left(\frac{z*\sigma}{E}\right)^2\\\\n \approx \left(\frac{1.645*2.6}{0.03}\right)^2\\\\n \approx 20325.254444 \\\\$

Round this up to the nearest integer to get 20326. For min sample size problems, <u>always</u> round up.

<h3>Answer: 20326</h3>

6 0

2 years ago