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3 years ago

13

If there are 1000 mosquitoes initially and there are 1600 after 1 day, what is the size of the colony after 2 days? How long is

it until there are 30,000 mosquitoes?

1 answer:

vlabodo [156]3 years ago

4 0

After two days there will be 2,560 mosquitoes.
It will take 8 days to reach at least 30,000 mosquitoes.

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A researcher examines 27 water samples for mercury concentration. The mean mercury concentration for the sample data is 0.097 cc

jonny [76]

Answer:

Step-by-step explanation:

Confidence interval is written in the form,

(Sample mean - margin of error, sample mean + margin of error)

The sample mean, x is the point estimate for the population mean.

Margin of error = z × s/√n

Where

s = sample standard deviation = 0.0074

n = number of samples = 27

From the information given, the population standard deviation is unknown and the sample size is small, hence, we would use the t distribution to find the z score

In order to use the t distribution, we would determine the degree of freedom, df for the sample.

df = n - 1 = 27 - 1 = 26

Since confidence level = 90% = 0.90, α = 1 - CL = 1 – 0.9 = 0.1

α/2 = 0.1/2 = 0.05

the area to the right of z0.05 is 0.05 and the area to the left of z0.05 is 1 - 0.05 = 0.95

Looking at the t distribution table,

z = 1.706

The critical value is 1.706

Margin of error = 1.706 × 0.0074√27

= 0.0024

The 90% confidence interval is

0.097 ± 0.0024

4 0

3 years ago

95×2 the answer to problem is

KengaRu [80]

95 times 2 is 190.

90 times 2 is 180, and 5 times 2 is 10.

180 + 10 = 190.

3 0

3 years ago

Read 2 more answers

Please help asap!

Furkat [3]

8 - 2/x the x is the denominator

6 0

3 years ago

Let φ(x, y) = arctan (y/x) .

Alexandra [31]

Answer:

a) $\large F(x,y)=(-\frac{y}{x^2+y^2},\frac{x}{x^2+y^2})$

b) $\large \mathbb{R}^2-\{(0,0)\}$

c) the points of the form (x, -x) for x≠0

Step-by-step explanation:

a)

If φ(x, y) = arctan (y/x), the vector field F = ∇φ would be

$\large F(x,y)=(\frac{\partial \phi}{\partial x},\frac{\partial \phi}{\partial y})$

On one hand we have,

$\large \frac{\partial \phi}{\partial x}=\frac{\partial arctan(y/x)}{\partial x}=\frac{-y/x^2}{1+(y/x)^2}=-\frac{y/x^2}{1+y^2/x^2}=\\\\=-\frac{y/x^2}{(x^2+y^2)/x^2}=-\frac{y}{x^2+y^2}$

On the other hand,

$\large \frac{\partial \phi}{\partial y}=\frac{\partial arctan(y/x)}{\partial y}=\frac{1/x}{1+(y/x)^2}=\frac{1/x}{1+y^2/x^2}=\\\\=\frac{1/x}{(x^2+y^2)/x^2}=\frac{x}{x^2+y^2}$

So

$\large F(x,y)=(-\frac{y}{x^2+y^2},\frac{x}{x^2+y^2})$

b)

The domain of definition of F is

$\large \mathbb{R}^2-\{(0,0)\}$

i.e., all the plane X-Y except the (0,0)

c)

Here we want to find all the points such that

$\large (-\frac{y}{x^2+y^2},\frac{x}{x^2+y^2})=(k,k)$

where k is a real number other than 0.

But this means

$\large -\frac{y}{x^2+y^2}=\frac{x}{x^2+y^2}\Rightarrow y=-x$

So, all the points in the line y = -x except (0,0) are parallel to the vector field F, that is, the points (x, -x) with x≠ 0

8 0

3 years ago

MN and KL are parallel. If JM = 6, MK = 12, and LN = 18, what is NJ?

Galina-37 [17]

6/12=X/18
Using the ratio of 18:12, you multiply 18/12 with 6, which equals 9.

Answer: NJ=9

5 0

3 years ago

Read 2 more answers