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2 years ago

Simplify: (–4) • (9) – (5) • (–2) A)2 B)–36 C)–26 D)82

Mathematics

1 answer:

lapo4ka [179]2 years ago

7 0

Using the correct order of operations, your equation would simplify as:
-36 - 10 = -26

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A bacteria population experiences continuous growth. If there were 2,000 bacteria present at the start of an experiment, how lon

allochka39001 [22]

Answer:

D. About 15.69 hours.

Step-by-step explanation:

Let x be the number of hours.

We have been given that there were 2,000 bacteria present at the start of an experiment and the growth rate was 7% per hour.

Since number of bacteria is growing exponentially, so we will use exponential growth function to solve our given problem.

The continuous exponential growth formula is in form: $y=e^{kx}$ , where,

e= mathematical constant,

k = Growth rate in decimal form.

Let us convert our given rate in decimal form.

$7\%=\frac{7}{100}=0.07$

Upon substituting our given values we will get exponential function for bacteria growth as: $y=2,000*e^{0.07x}$ , where, y represents number of bacteria after x hours.

Since we need to figure out the number of hours it will take for there to be 6,000 bacteria, so we will substitute y= 6,000 in our function.

$6,000=2,000*e^{0.07x}$

Let us divide both sides of our equation by 2,000.

$\frac{6,000}{2,000}=\frac{2,000*e^{0.07x}}{2,000}$

$3=e^{0.07x}$

Let us take natural log of both sides of our equation.

$\text{ln}(3)=ln(e^{0.07x})$

$\text{ln}(3)=0.07x$

$1.0986122=0.07x$

$x=\frac{1.0986122}{0.07}$

$x=15.69446\approx 15.69$

Therefore, it will take about 15.69 hours to be 6,000 bacteria and option D is the correct choice.

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3 years ago

Which property is illustrated by the following statement? 6 + (x + 8) = ( 6 + x) + 8 Commutative Property of Addition Associativ

AnnyKZ [126]

Answer:

Commutative Property of Multiplication, I believe. Hope this helps!

Step-by-step explanation:

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3 years ago

Read 2 more answers

Ratio and proportion :21:2x=7:10

jenyasd209 [6]

Answer:

x=15

Step-by-step explanation:

21:2x=7:10 can be rewritten as 21/2x=7/10

21/2x=7/10, cross multiply

= 14x=210

x=15

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2 years ago

The Federal Government is stepping up efforts to reduce average response times of fire departments to fire calls. Nationwide, th

TiliK225 [7]

Answer: in order to qualify, the time must be at least 15.93 minutes

Step-by-step explanation:

Let x be a random variable representing the average response times of fire departments to fire calls. Since it follows a normal distribution, we will determine the z score by applying the formula,

z = (x - µ)/σ

Where

x = sample mean

µ = population mean

σ = population standard deviation

From the information given,

µ = 12.8 minutes

σ = 3.7 minutes

in order to qualify for the special safety award, the probability value would be to the right of the z score corresponding to 80%

The z score corresponding to 80% on the normal distribution table is 0.845

Therefore,

0.845 = (x - 12.8)/3.7

0.845 × 3.7 = x - 12.8

3.13 = x - 12.8

x = 12.8 + 3.13 = 15.93

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2 years ago

1. Select all of the fraction models that are equivalent. d.

guajiro [1.7K]

Answer:

A,D,C

Step-by-step explanation:

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2 years ago