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prohojiy [21]
2 years ago
14

A bacteria culture initially contains 100 cells and grows at a rate proportional to its size. After an hour the population has i

ncreased to 420. Find the rate of growth after 3 hours.
Mathematics
2 answers:
Assoli18 [71]2 years ago
8 0

Step-by-step explanation:

Rate of growth equals 420/100 = 4.2 times per hour

So after t=three hours,

size of culture = 100*(4.2)^t = 100*4.2^3=7408.8 bacteria,

round to nearest unit 7409 bacteria after three hours (after initial size of 100).

prohojiy [21]2 years ago
6 0

Answer:

a) 100•4.2^t

b) P(3)= about 7409 bacteria

c) P’(3)= about 10,632 bacteria per hour

d) t= about 3.2 hours

Step-by-step explanation:

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Richie spent $120 on 12 rose bushes and 2 gardenias, while Jim spent it $150 on 10 rose bushes and 10 gardenias. What is the cos
Basile [38]
With the given information, we can create several equations:

120 = 12x + 2y
150 = 10x + 10y

With x being the number of rose bushes, and y being the number of gardenias.

To find the values of the variables, we can use two methods: Substitution or Elimination

For this case, let us use elimination. To begin, let's be clear that we are going to be adding these equations together. Therefore, in order to get the value of one variable, we must cancel one of them out - it could be x or y, it doesn't matter which one you decide to cancel out. Let's cancel the x out:

We first need to multiply the equations by numbers that would cause the x's to cancel out - and this can be done as follows:

-10(120 = 12x + 2y)
 12(150 = 10x + 10y) => Notice how one of these is negative

Multiply out:

    -1200 = -120x - 20y
 +  1800 =  120x + 120y          => Add these two equations together
---------------------------------
600 = 100y

Now we can solve for y:

y = 6

With this value of y known, we can then pick an equation from the beginning of the question, and plug y in to solve for x:

120 = 12x + 2y    =>    120 = 12x + 2(6)

Now we can solve for x:

120 = 12x + 12    =>     108 = 12x

x = 9

So now we know that x = 9, and y = 6.

With rose bushes being x, we now know that the cost of 1 rose bush is $9.
With gardenias being y, we now know that the cost of 1 gardenia is $6.  
4 0
3 years ago
Suppose a 90% confidence interval for the mean salary of college graduates in a town in Mississippi is given by [$38,737, $50,46
JulsSmile [24]

Answer:

a. The point estimate was of $44,600.

b. The sample size was of 16.

Step-by-step explanation:

Confidence interval concepts:

A confidence interval has two bounds, a lower bound and an upper bound.

A confidence interval is symmetric, which means that the point estimate used is the mid point between these two bounds, that is, the mean of the two bounds.

The margin of error is the difference between the two bounds, divided by 2.

a. What is the point estimate of the mean salary for all college graduates in this town?

Mean of the bounds, so:

(38737+50463)/2 = 44600.

The point estimate was of $44,600.

b. Determine the sample size used for the analysis.

First we need to find the margin of error, so:

M = \frac{50463-38737}{2} = 5863

Relating the margin of error with the sample size:

We have that to find our \alpha level, that is the subtraction of 1 by the confidence interval divided by 2. So:

\alpha = \frac{1 - 0.9}{2} = 0.05

Now, we have to find z in the Z-table as such z has a p-value of 1 - \alpha.

That is z with a pvalue of 1 - 0.05 = 0.95, so Z = 1.64.

Now, find the margin of error M as such

M = z\frac{\sigma}{\sqrt{n}}

In which \sigma is the standard deviation of the population and n is the size of the sample.

For this problem, we have that \sigma = 14300, M = 5863. So

M = z\frac{\sigma}{\sqrt{n}}

5863 = 1.645\frac{14300}{\sqrt{n}}

5863\sqrt{n} = 1.645*14300

\sqrt{n} = \frac{1.645*14300}{5863}

(\sqrt{n})^2 = (\frac{1.645*14300}{5863})^2

n = 16

The sample size was of 16.

7 0
3 years ago
HELP!!! I WILL MARK BRAINLEST!
agasfer [191]

Answer:

B: (16,32)

Step-by-step explanation:

Please give brainlest

4 0
3 years ago
Read 2 more answers
……………………868685758584984444
nydimaria [60]
???444489485857586868........................
7 0
2 years ago
Read 2 more answers
Which value of x will make the triangles similar by the SSS similarity theorem
masha68 [24]

Answer:

x = 30.

Step-by-step explanation:

For the triangles to be similar corresponding sides must be in the same ratio.

So 50/ 75 = x / 45

75x = 50*45

x = 50* 45/75

= 2 * 45 / 3

= 30.   (answer).


4 0
3 years ago
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