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3 years ago

The interquartile range (IQR) for thedata:32,7,3,-5,1,8, 10,36 is :

Mathematics

1 answer:

GenaCL600 [577]3 years ago

7 0

Answer:

Your Interquartile range (IQR) would be 19.

Step-by-step explanation:

-5, 1, 3, 7, 8, 10, 32, 36

Median: 7.5

Lower quartile: 2

Upper quartile: 21

Interquartile range: 21 - 2 = 19

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What's the quotient of I? 5+5i divided by 2+I

sladkih [1.3K]

$if\ "i"\ is\ the\ imaginary\ unit:\sqrt{-1}=i\Rightarrow i^2=-1\\\\then\\\\\frac{5+5i}{2+i}=\frac{5+5i}{2+i}\cdot\frac{2-i}{2-i}=\frac{10-5i+10i+5i^2}{2^2-i^2}=\frac{10+5i-5}{4+1}=\frac{5+5i}{5}=\boxed{1+i}$

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3 years ago

A bacteria culture starts with 400 bacteria and grows at a rate proportional to its size. After 4 hours, there are 9000 bacteria

Kaylis [27]

Answer:

A) The expression for the number of bacteria is $P(t) = 400e^{0.7783t}$ .

B) After 5 hours there will be 19593 bacteria.

C) After 5.55 hours the population of bacteria will reach 30000.

Step-by-step explanation:

A) Here we have a problem with differential equations. Recall that we can interpret the rate of change of a magnitude as its derivative. So, as the rate change proportionally to the size of the population, we have

$P' = kP$

where $P$ stands for the population of bacteria.

Writing $P'$ as $\frac{dP}{dt}$ , we get

$\frac{dP}{dt} = kP$ .

Notice that this is a separable equation, so

$\frac{dP}{P} = kdt$ .

Then, integrating in both sides of the equality:

$\int\frac{dP}{P} = \int kdt$ .

We have,

$\ln P = kt+C$ .

Now, taking exponential

$P(t) = Ce^{kt}$ .

The next step is to find the value for the constant $C$ . We do this using the initial condition $P(0)=400$ . Recall that this is the initial population of bacteria. So,

$400 = P(0) = Ce^{k0}=C$ .

Hence, the expression becomes

$P(t) = 400e^{kt}$ .

Now, we find the value for $k$ . We are going to use that $P(4)=9000$ . Notice that

$9000 = 400e^{k4}$ .

Then,

$\frac{90}{4} = e^{4k}$ .

Taking logarithm

$\ln\frac{90}{4} = 4k$ , so $\frac{1}{4}\ln\frac{90}{4} = k$ .

So, $k=0.7783788273$ , and approximating to the fourth decimal place we can take $k=0.7783$ . Hence,

$P(t) = 400e^{0.7783t}$ .

B) To find the number of bacteria after 5 hours, we only need to evaluate the expression we have obtained in the previous exercise:

$P(5) =400e^{0.7783*5} = 19593.723 \approx 19593$ .

C) In this case we want to do the reverse operation: we want to find the value of t such that

$30000 = 400e^{0.7783t}$ .

This expression is equivalent to

$75 = e^{0.7783t}$ .

Now, taking logarithm we have

$\ln 75 = 0.7783t$ .

Finally,

$t = \frac{\ln 75}{0.7783} \approx 5.55$ .

So, after 5.55 hours the population of bacteria will reach 30000.

6 0

3 years ago

What is the quotient of 2 3/4 and 5 1/2?

Juli2301 [7.4K]

Answer:

1/2

Step-by-step explanation:

This can be done several ways. Perhaps the easiest is to use the decimal equivalents:

(2 3/4)/(5 1/2) = 2.75/5.5 = 0.5

If you want to use the numbers given, the usual procedure is to convert them to improper fractions and do the division that way:

2 3/4 = (4·2 +3)/4 = 11/4

5 1/2 = (2·5 +1)/2 = 11/2

Now, the problem can be written as ...

(2 3/4) / (5 1/2) = (11/4) / (11/2)

This sort of division problem can be solved two ways:

invert and multiply (the denominator is inverted)

= (11/4) × (2/11) = (11·2)/(11·4) = 2/4 = 1/2

use a common denominator (for the two fractions)

= (11/4) / (11/2) = (11/4) / (22/4) = 11/22 = 1/2

The quotient is 1/2.

_____

Additional comments

It is helpful in many cases to just use decimal equivalents for the calculation. To do that, you need to be familiar with the equivalents of commonly used fractions. I find it is usually sufficient to know the unit fractions in each case. Then you can multiply or add to find the others.

1/9 = 0.1...(1-digit repeat), 1/8 = 0.125, 1/7 = 0.142857...(6-digit repeat), 1/6 = 0.16...(1-digit repeat), 1/5 = 0.2, 1/4 = 0.25, 1/3 = 0.3...(1-digit repeat), 1/2 = 0.5

I learned the "invert and multiply" method for dividing fractions when I was in school. The Common Core math apparently also teaches the method of matching the denominators of a compound fraction. Then the result is the ratio of numerators. (A variation not taught is that you can match the numerators and use the inverse of the ratio of denominators. Both of these methods can be validated using the "invert and multiply" method. (11/4)/(11/2) = 2/4)

"Invert and multiply" is another way of saying that division is the same as multiplication by the reciprocal. This applies everywhere, not just in fraction problems.

8 0

3 years ago

CHOOSE TO ANSWER EITHER QUESTION:

Ugo [173]

Answer:

First one: C. Second One:C.

Step-by-step explanation:

Kate purchased a car for $23,000. It will depreciate by a rate of 12% a year. What is the value of the car in 4 years?

a) $13,935.76

b) $12,874.57

c) $13,792.99

To solve this this is an exponential function. The price started at $23,000 and depreciates at 12% so the equation is f(x) = (23,0000)(1-0.12)^4. When calculated results with 13792.99328 which is C.

A rare coin is currently worth $450. The value of the coin increases 4% each year. Determine the value of the coin after 7 years.

a) $613.98

b) $546.78

c) $592.17

To solve this this is also an exponential function. The price started at $450 and the coin increases 4% each year so the equation is f(x) = (450)(1+0.04)^7. When calculated results with 592.169300656 which is c.

4 0

2 years ago

Logan multiplied 54,216 by a number less than 1. He thinks the product will be greater than 54,216. Explain why he is incorrect.

kicyunya [14]

He is incorrect because anything mutipled by 0 is 0!

8 0

3 years ago

The interquartile range (IQR) for thedata:32,7,3,-5,1,8, 10,36 is :​

The interquartile range (IQR) for thedata:32,7,3,-5,1,8, 10,36 is :