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dexar [7]
3 years ago
11

A species of dolphins is decreasing at a rate of 3.1% per year. If there are currently 20,000 dolphins, how many will there be i

n 30 years?
Mathematics
1 answer:
Alenkinab [10]3 years ago
5 0

Answer:

About 7,776 dolphins

Step-by-step explanation:

we know that

The equation of a exponential decay function is given by

y=a(1-r)^x

where

y is the number of species of dolphins

x is the number of years

a is the initial value

r is the rate of change

we have

a=20,000\\r=3.1\%=3.1/100=0.031

substitute

y=20,000(1-0.031)^x

y=20,000(0.969)^x

How many dolphins will there be in 30 years?

For x=30 years

substitute in the equation

y=20,000(0.969)^{30}=7,776

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PLEASEEE HURRYYY
Masteriza [31]

Answer:

(2,-5) and (2,1).

Step-by-step explanation:

We need to find the find all the points having an x coordinate of 2 whose distance from the point (-2,-4) is 5.

A circle with center (-2,-4) and radius 5 represents all the points whose distance from the point (-2,-4) is 5.

Standard form of a circle is

(x-h)^2+(y-k)^2=r^2

where, (h,k) is center and r is the radius.

(x-(-2))^2+(y-(-4))^2=(5)^2

(x+2)^2+(y+2)^2=25

Now, put x=2.

(2+2)^2+(y+2)^2=25

(4)^2+(y+2)^2=25

(y+2)^2=25-16

(y+2)^2=9

Taking square root on both sides.

y+2=\pm\sqrt{9}

y+2=\pm3

y+2=-3\text{ or }y+2=3

y=-5\text{ or }y=1

So, the y-coordinates of the points are -5 and 1.

Therefore, the required points are (2,-5) and (2,1).

8 0
2 years ago
You roll a six sided die what is the probability of rolling a 4 or an odd number
12345 [234]

Answer:

we need an out of sorry -_-

5 0
3 years ago
Read 2 more answers
You are planning to invest $5000 in an account earning 9% per year for retirement. a. If you put the $5000 in an account at age
ICE Princess25 [194]

Answer:

A).Amount = $218250

B). Amount = $88700

Step-by-step explanation:

A) .$5000 in an account at age 23, and withdraw it 42 years

Number of years t= 42 years

Principal P = $5000

Rate r= 9%

Number of times compounded n= 42

A= p(1+r/n)^(nt)

A= 5000(1+0.09/42)^(42*42)

A= 5000(1+0.002143)^(1764)

A= 5000(1.002143)^1764

A= 5000(43.65)

A= 218250

Amount = $218250

B).waits 10 years before making the deposit, so that it stays in the account for only 32 years

Number of years t= 32 years

Principal P = $5000

Rate r= 9%

Number of times compounded n= 32

A= p(1+r/n)^(nt)

A= 5000(1+0.09/32)^(32*32)

A= A= 5000(1+0.0028125)^(1024)

A= 5000(1.0028125)^1024

A= 5000(17.74)

A= 88700

Amount = $88700

5 0
2 years ago
This recipe makes 4 portions of potato soup.
Dominik [7]

Answer:

120 ml oil

150g onions

1.2 kg potatoes

1.5 litres milk

Step-by-step explanation:

The revipe serves 4 people, but Richard wants to serve 12 people. This is 3x the number of people intended.

So, multiply all the fiven ingredients by 3 as well.

Oil = 40ml x 3 = 120ml

Onions = 50g x 3 = 150g

Potatoes = 400g x 3 = 1200g = 1.2 kg

Milk = 500ml x 3 = 1500ml = 1.5 litres

Hope this helps

4 0
2 years ago
Read 2 more answers
An underground conical tank has a top diameter of 4m and a depth of 6m. Compute the capacity of the tank in cubic meter.
dlinn [17]

Step-by-step explanation:

1/3πr^2h

{(1/3)×(22/7)×2^2×6}m^3

[(1/3)×(22/7)×4×6)}m^3

{528/21}m^3

=25.1 m^3

NOTE:r=diameter divided by 2

7 0
3 years ago
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