Oak wilt is a fungal disease that infects oak trees. Scientists have discovered that a single tree in a small forest is infected with oak wilt. They determined that they can use this exponential model to predict the number of trees in the forest that will be infected after t years.
f(t) = e^0.4t
The scientists believe the forest will be seriously damaged when 21 or more of the forest’s 200 oak trees are infected by oat wilt. According to their model, how many years will it take for 21 of the trees to become infected?

Type the correct answer in the box. Use numerals instead of words. Round your answer to the nearest tenth.

Answers

Answer 1

To solve this question, we need to solve an exponential equation, which we do applying the natural logarithm to both sides of the equation, getting that it will take 7.6 years for for 21 of the trees to become infected.

Model:

The exponential model for the number of infected trees after t years is given by:

[tex]f(t) = e^{0.4t}[/tex]

How many years will it take for 21 of the trees to become infected?

This is t for which:

[tex]f(t) = 21[/tex]

Thus

[tex]e^{0.4t} = 21[/tex]

Applying the natural logarithm to both sides:

[tex]\ln{e^{0.4t}} = \ln{21}[/tex]

[tex]0.4t = \ln{21}[/tex]

[tex]t = \frac{\ln{21}}{0.4}[/tex]

[tex]t = 7.6[/tex]

It will take 7.6 years for for 21 of the trees to become infected.

For another example of a problem in which an exponential equation is solved, you can check brainly.com/question/24290183.


Related Questions

A square garden has area 1764meter find it's length and perimeter

Answers

Answer:

[tex]area \: of \: a \: squre = {a}^{2} \\ {a}^{2} = 176 \\ a = 13.26m \\ perimeter = 4a = 4 \times 13.26 = 53.04m^2 \\ thank \: you[/tex]

Answer:

Length = 42 mPerimeter = 168 m

Concept:

Here, we need to know how to find the area and perimeter of the square.

Area (square) = s²

s = side length

Perimeter (square) = 4s

s = side length

Solve:

PART I: Find the length

Given information

Area = 1764 m²

Given formula

A = s²

Substitute values into the formula

1764 = s²

Square root both sides

√s² = √1764

[tex]\boxed{s=42m}[/tex]

--------------------------------------------------------------------------------------------------------

PART II: Find the perimeter

Given information

s = 42 m

Given formula

P = 4s

Substitute values into the formula

P = 4 (42)

Simplify by multiplication

[tex]\boxed{P=168m}[/tex]

Hope this helps!! :)

Please let me know if you have any questions

9.
A rocket is launched from the top of a 76-foot cliff with an initial velocity of 135 ft/s. a. Substitute the values into the vertical motion formula h = –16t2 + vt + c. Let h = 0. b. Use the quadratic formula to find out how long the rocket will take to hit the ground after it is launched. Round to the nearest tenth of a second.


A. 0 = –16t2 + 135t + 76; 0.5 s

B. 0 = –16t2 + 76t + 135; 9 s

C. 0 = –16t2 + 76t + 135; 0.5 s

D. 0 = –16t2 + 135t + 76; 9 s

Answers

Answer:

The answer is 2.)

Step-by-step explanation:

Given initial velocity=135 ft/s

& cliff=76 foot

Given quadratic equation

⇒                      (let h=0 it is given)

⇒  

⇒  

⇒    t=8.96≈9 s (the other root is negative)

Hence, rocket will take 9 s to hit the ground after launched.

Answer:  Choice D

0 = 16t^2 + 135t + 76;  9 s

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

Explanation:

The equation we start with is

[tex]h = -16t^2 + vt + c\\\\[/tex]

where v is the starting or initial velocity, and c is the starting height.

We're told that v = 135 and c = 76

We let h = 0 to indicate when the object hits the ground, aka the height is 0 ft.

That means the equation updates to [tex]0 = -16t^2 + 135t + 76\\\\[/tex]

Based on that alone, the answer is between A or D

-------------------

We'll use the quadratic formula to solve for t

We have

a = -16b = 135c = 76

So,

[tex]t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\\\\t = \frac{-135 \pm \sqrt{135^2 - 4(-16)(76)}}{2(-16)}\\\\t = \frac{-135 \pm \sqrt{23,089}}{-32}\\\\t \approx \frac{-135 \pm 151.9506}{-32}\\\\t \approx \frac{-135 + 151.9506}{-32} \ \text{ or } \ t \approx \frac{-135 - 151.9506}{-32}\\\\t \approx \frac{16.9506}{-32} \ \text{ or } \ t \approx \frac{-286.9506}{-32}\\\\t \approx -0.52971 \ \text{ or } \ t \approx 8.96721\\\\[/tex]

We ignore the negative t value because a negative time duration makes no sense.

The only practical solution here is roughly 8.96721 which rounds to 9.0 or simply 9 when we round to the nearest tenth (one decimal place).

In short, the object will hit the ground at the 9 second mark roughly. Or put another way: the object is in the air for about 9 seconds.

From this, we can see that the final answer is choice D.

Keep in mind that we aren't accounting for any wind resistance. Considering this variable greatly complicates the problem and requires much higher level mathematics. So we just assume that there is no wind at this moment.

Sayad bought a watch and sold to Dakshes at 10% profit. Sayad again sold it to Sahayata for rs 6,050 at 10% profit. i)Find the cost price of Dakshes. ii) Find the cost price of Sayad.​

Answers

Answer:

The cost price of Dakshes was $ 5,500, while the cost price of Sayad was $ 5,000.

Step-by-step explanation:

Given that Sayad bought a watch and sold to Dakshes at 10% profit, and Dakshes again sold it to Sahayata for $ 6,050 at 10% profit, to find the cost price of Dakshes and the cost price of Sayad the following calculations must be performed:

6,050 / 1.1 = X

5,500 = X

5,500 / 1.1 = X

5,000 = X

Therefore, the cost price of Dakshes was $ 5,500, while the cost price of Sayad was $ 5,000.

find the value of a and b if [tex]5+√3/7+2√3=a-b√3[/tex]

Answers

Answer:

The values of [tex]a[/tex] and [tex]b[/tex] are [tex]5[/tex] and [tex]-\frac{15}{7}[/tex], respectively.

Step-by-step explanation:

There are mistakes in the statement, correct form is presented below:

[tex]5+\frac{\sqrt{3}}{7} + 2\sqrt{3} = a - b\cdot \sqrt{3}[/tex].

By direct comparison we have the following system of equations:

[tex]a = 5[/tex] (1)

[tex]\frac{\sqrt{3}}{7}+2\sqrt{3} = -b\cdot \sqrt{3}[/tex] (2)

In (2) we solve for [tex]b[/tex]:

[tex]\left(\frac{1}{7}+2 \right)\cdot \sqrt{3} = -b\cdot \sqrt{3}[/tex]

[tex]b = -\frac{15}{7}[/tex]

The values of [tex]a[/tex] and [tex]b[/tex] are [tex]5[/tex] and [tex]-\frac{15}{7}[/tex], respectively.

Which quadratic formula do I need to use to solve 2x(x+1.5)=-1

Answers

Answer:

x = - 1, x = - 0.5

Step-by-step explanation:

Given

2x(x + 1.5) = - 1 ← distribute parenthesis on left side

2x² + 3x = - 1 ( add 1 to both sides )

2x² + 3x + 1 = 0 ← in standard form

(2x + 1)(x + 1) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 1 = 0 ⇒ x = - 1

2x + 1 = 0 ⇒ 2x = - 1 ⇒ x = - 0.5


often contains information about the author's experiences with the subject matter of
9. The author's introduction to a book, also called a/an
the book.
A. glossary
B. Index
C. table of contents
D. preface


Im quite sure it’s d wanna make sure

Answers

you’re correct, it’s d
The answer is D - preface.

Which rules define the function graphed below? (15 points cuz I'm stumped)

y=2x+3; y=-1/3x+3
y=2x; y=-1/3x
y=3x+2; y=3x-1
y=-3x+3; y=x+3

Answers

Answer:  Choice A

y=2x+3; y=-1/3x+3

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

Explanation:

The left portion of the blue curve is y = 2x+3 but it is only graphed when x < 0 (we could argue that [tex]x \le 0[/tex] but I'll set that aside for the other portion).

The right portion is the line y = -1/3x + 3 and it's only graphed when [tex]x \ge 0[/tex]

So we could have this piecewise function

[tex]f(x) = \begin{cases}2x+3 \ \text{ if } x < 0\\-\frac{1}{3}x+3 \ \text{ if } x \ge 0\\\end{cases}[/tex]

Or we could easily swap the "or equal to" portion to move to the first part instead like this

[tex]f(x) = \begin{cases}2x+3 \ \text{ if } x \le 0\\-\frac{1}{3}x+3 \ \text{ if } x > 0\\\end{cases}[/tex]

Either way, we're involving the equations mentioned in choice A

I really really need help with this

Answers

Answer:

c) 21

Step-by-step explanation:

[tex] \sqrt{169} + \sqrt{64} [/tex]

13+8

answer is 21

Solve BCD. Round the answers to the nearest hundredth, if necessary.

Answers

Answer:

B

Step-by-step explanation:

here we use trigonometric ratio involving soh,cah,toa

Jia baked two kinds of muffins. She baked 27 blueberry muffins. The number of cranberry muffins she baked is represented by the equation shown.

27 ÷ 3 = 9
Which statement accurately compares the number of blueberry muffins and the number of cranberry muffins?

Jia baked 3 times as many blueberry muffins as cranberry muffins.
Jia baked 9 times as many blueberry muffins as cranberry muffins.
Jia baked 3 times as many cranberry muffins as blueberry muffins.
Jia baked 9 times as many cranberry muffins as blueberry muffins.

Answers

Answer:

she baked 3 times as many cranberry than blueberry muffins

Step-by-step explanation:

i think that because 9×3=27

the amount of the cranberry muffins are 9

Analyze the diagram below and complete the instructions that follow.
10
6
B.
'C С
8
Find sin ZA
A 3
5
B. 4
C 1

Answers

Answer:

B. 4/5

Step-by-step explanation:

Sin = Opposite/Hypotenuse

Sin∠A = 8/10 = 4/5

i  genuinely dont know help

Answers

Answer:

-13 1/2 < -6/8

Step-by-step explanation:

*Any negative in either the numerator or denominator will make the entire fraction negative.

1/2  = .5

-13 1/2 = -13.5

-6/8 = -3/4

-3/4 = -0.75

-6/8 = -0.75

-13 1/2 = -13.5

Which means:

-13 1/2 < -6/8

Hope this helped.

Answer:

[tex] < [/tex]

Step-by-step explanation:

[tex] \frac{6}{8} [/tex]

Is close to 0 (to positive) you can use a time line to determine which is a correct answer

Which graph represents a linear function

Answers

Answer:

c on edge

Step-by-step explanation:

What are the coordinates of the vertices of the image?
A) A'(9,8), B'(-3,-4), C'(1, 2), and D'(1,-2)
B) A'(3,4), B'(3,-4), C'(-5, 2), and D'(1, 2)
C) A'(3,8), B'(-3, 4), C'(1,-2), and D'(-1,2)
D) A'(-3, 4), B'(3,4), C'(5,-2), and D'(-1,-2)​

Answers

The answer is D good luck

Answer:

D

Step-by-step explanation:

I took the quiz

Identify a transformation of the function f(x)
x2 by observing the equation of the function g(x) = (x - 6)^2

Answers

Answer:

2nd option

Step-by-step explanation:

Given f(x) then f(x + a) is a horizontal translation of f(x)

• If a > 0 then a shift left of a units

• If a < 0 then a shift right of a units

Here g(x) = (x - 6)²

The base graph has been shifted right 6 units

what is the commutative property for 4xy
PLEASE ANSWER QUICKLY

Answers

Answer:

[tex]we \: know \: that \: commutative \: prop \\ = x + y = y + x \\ then \\ 4xy + 0 = 0 + 4xy \\ thank \: you[/tex]

round 1.89 to one decimal place

Answers

Answer:

1.9

Step-by-step explanation:

You round when the numbers behind the decimal are 5 or greater. This being said, you need to round from the number furthest away from the decimal. In this case it would be 9. 9 is greater than 5 so we round 8 up to 9 and get rid of the number behind it. We are left with 1.9

Urgent ! Help me please

Answers

Answer:

B

Step-by-step explanation:

x -> x and y -> y+5

-1 -> - 1 and - 3 -> 2, so b is the correct answer.

I need help right now ASAP!!!please man some on help me

Answers

Answer:

hope it helps

Step-by-step explanation:

Answer:

Step-by-step explanation:

S is the midpoint of QR.

⇒ RS = QS    

QR ⊥ PS

⇒ ∠RSP = ∠QSP = 90°

In ΔPSR & ΔPSQ,

Statement                     Reason

RS ≅ QS                       S is midpoint of QR

∠RSP ≅ ∠QSP              QR ⊥ PS

PS ≅ PS                         Reflexive property

ΔPSR ≅ ΔPSQ               Side Angle Side - S A S Congruent

PR≅  PQ                        CPCTC

If f(x)=7 find x=-3

A.4
B.-3
C.7
D.-4

Answers

Answer: the answer to your question is 7

Step-by-step explanation:

paul leaves for school at 7:25 am he returned home at 3:15 pm how long was paul away from home?

Answers

Answer:

8 hours 10 minutes

I hope this answers your question

Answer: paul has been away from home for 7 hours and 50 minutes.

Step-by-step explanation:

f(x) = x+3
g(x) = 2x^2-4
find (f times g) (x)

Answers

Step-by-step explanation:

(f*g) (x)=f(x) * g(x)

=(x+3)(2x^2-4)

=2x^3-4x+6x^2-12

What are the different ways you can solve a system of linear equations in two variables? What is the process for solving a system using each method?

Answers

The method is pendmas

39.) Fiona bought a brand new Harley Davidson motorcycle. Since the weather was nice, she decided to go out for a ride with some of her friends. Before leaving town, she stopped to fill up her motorcycle with gas so that she had a full tank. If Fiona's motorcycle has a 4 gallon gas tank, and she only had to add 2 4/7 gallons, how much gas was in the tank before she filled up?​

Answers

Answer:

1 3/7 gallons

Step-by-step explanation:

Let the amount of gas in the tank before filling was x.

We have:

x + 2 4/7 = 4x = 4 - 2 4/7x = 2 - 4/7x = 1 3/7 gallons

let the amount of gas be x

[tex]\\ \sf\longmapsto x+2\dfrac{4}{7}=4[/tex]

[tex]\\ \sf\longmapsto x+\dfrac{18}{7}=4[/tex]

[tex]\\ \sf\longmapsto x=4-\dfrac{18}{7}[/tex]

[tex]\\ \sf\longmapsto x=\dfrac{28-18}{7}[/tex]

[tex]\\ \sf\longmapsto x=\dfrac{10}{7}[/tex]

[tex]\\ \sf\longmapsto x=1\dfrac{3}{7}[/tex]

what's the formula of


(a+b)³ = ?

Answers

Answer:

(a+b)³=a³+3a²b+3ab²+b³

Answer:

Step-by-step explanation:

Hello!

(a+b)(a+b)(a+b)

(a+b)(a+b) = a²+2ab + b²

(a²+2ab + b²) (a+b)=

a³ + a²b +  2a²b + 2ab² + ab² + b³ =

a³ + b³ +  2a²b + 2ab² + ab²  + a²b

in the first quarter austin played for 4 minutes and 30 seconds. wyatt played for 310 seconds who had more playing time

Answers

Answer:

wyatt

Step-by-step explanation:

4:30 mins is 270 seconds

sentence
After several days of drilling, a water well is 80
meters deep. The well is being drilled at a rate of
20 meters per day.
How many more days will it take to reach a total
depth of 180 meters?

Answers

Answer:

it will take 5days to reach a total of 180meters

Step-by-step explanation:

80m+20+20+20+20+20

=180meters

=5days

The membership fee for joining a gardening association is
$24 per year. A local botanical garden charges members of the gardening association
$3 for admission to the garden. Nonmembers of the association are charred $6.
After how many visits to the garden is the total cost for members, including the
the total cost for nonmembers?

Answers

Hi.

Let's call X number of visits.

so members pay for a year : membership 24 and reduce entrance at 3 dollars.

so you member pay : 3X+24

a non member pay entrance fee of 6 for each visit.

so 6X

Question : for how many visit would a membership will be more intresting than standar entrance ?

3X+24 = 6X

3X-6X = -24

-3X=-24

X= -24/-3

X =24/3

X= 8

Under 8 visit a year, it's cheaper non being a member.

at 8 entrance cost is the same for members and non member. After it better to choose membership as

9 entrances for member is : 3x9 +24 = 27+24= 51

non member : 9x6 = 54

And so on for each supplementary visits.

10700 by 100 + 5192by 1000 - 412

Answers

Answer:

the answer is -299.808 well that's what I think it's

Answer:

-299.808

Step-by-step explanation:

= 10700/100 + 5192/100 - 412

= 107 + 5.192 - 412

= -299.808

If the areas of two similar triangles are equal, prove that they are congruent

Answers

Refer the attached image for the answer

HOPE SO IT HELPS YOU

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