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3 years ago

9

Please help ill mark brilliant

1 answer:

USPshnik [31]3 years ago

8 0

Answer:

i think its 12

Step-by-step explanation:

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Joseph asked students in his homeroom class how many songs that have on their MP3 players. His data is recorded in the table bel

Neporo4naja [7]

Answer:

21

Step-by-step explanation:

Boys:

Q1: 78

Q3: 140

IQR: 140 - 78 = 62

Girls:

Q1: 97

Q3: 180

IQR: 180 - 97 = 83

Difference:

83 - 62

21

5 0

3 years ago

City A had a population of 10000 in the year 1990. City A’s population grows at a constant rate of 3% per year. City B has a pop

Georgia [21]

Answer:

City A and city B will have equal population 25years after 1990

Step-by-step explanation:

Given

Let

$t \to$ years after 1990

$A_t \to$ population function of city A

$B_t \to$ population function of city B

<u>City A</u>

$A_0 = 10000$ ---- initial population (1990)

$r_A =3\%$ --- rate

<u>City B</u>

$B_{10} = \frac{1}{2} * A_{10}$ ----- t = 10 in 2000

$A_{20} = B_{20} * (1 + 20\%)$ ---- t = 20 in 2010

Required

When they will have the same population

Both functions follow exponential function.

So, we have:

$A_t = A_0 * (1 + r_A)^t$

$B_t = B_0 * (1 + r_B)^t$

Calculate the population of city A in 2000 (t = 10)

$A_t = A_0 * (1 + r_A)^t$

$A_{10} = 10000 * (1 + 3\%)^{10}$

$A_{10} = 10000 * (1 + 0.03)^{10}$

$A_{10} = 10000 * (1.03)^{10}$

$A_{10} = 13439.16$

Calculate the population of city A in 2010 (t = 20)

$A_t = A_0 * (1 + r_A)^t$

$A_{20} = 10000 * (1 + 3\%)^{20}$

$A_{20} = 10000 * (1 + 0.03)^{20}$

$A_{20} = 10000 * (1.03)^{20}$

$A_{20} = 18061.11$

From the question, we have:

$B_{10} = \frac{1}{2} * A_{10}$ and $A_{20} = B_{20} * (1 + 20\%)$

$B_{10} = \frac{1}{2} * A_{10}$

$B_{10} = \frac{1}{2} * 13439.16$

$B_{10} = 6719.58$

$A_{20} = B_{20} * (1 + 20\%)$

$18061.11 = B_{20} * (1 + 20\%)$

$18061.11 = B_{20} * (1 + 0.20)$

$18061.11 = B_{20} * (1.20)$

Solve for B20

$B_{20} = \frac{18061.11}{1.20}$

$B_{20} = 15050.93$

$B_{10} = 6719.58$ and $B_{20} = 15050.93$ can be used to determine the function of city B

$B_t = B_0 * (1 + r_B)^t$

For: $B_{10} = 6719.58$

We have:

$B_{10} = B_0 * (1 + r_B)^{10}$

$B_0 * (1 + r_B)^{10} = 6719.58$

For: $B_{20} = 15050.93$

We have:

$B_{20} = B_0 * (1 + r_B)^{20}$

$B_0 * (1 + r_B)^{20} = 15050.93$

Divide $B_0 * (1 + r_B)^{20} = 15050.93$ by $B_0 * (1 + r_B)^{10} = 6719.58$

$\frac{B_0 * (1 + r_B)^{20}}{B_0 * (1 + r_B)^{10}} = \frac{15050.93}{6719.58}$

$\frac{(1 + r_B)^{20}}{(1 + r_B)^{10}} = 2.2399$

Apply law of indices

$(1 + r_B)^{20-10} = 2.2399$

$(1 + r_B)^{10} = 2.2399$ --- (1)

Take 10th root of both sides

$1 + r_B = \sqrt[10]{2.2399}$

$1 + r_B = 1.08$

Subtract 1 from both sides

$r_B = 0.08$

To calculate $B_0$ , we have:

$B_0 * (1 + r_B)^{10} = 6719.58$

Recall that: $(1 + r_B)^{10} = 2.2399$

So:

$B_0 * 2.2399 = 6719.58$

$B_0 = \frac{6719.58}{2.2399}$

$B_0 = 3000$

Hence:

$B_t = B_0 * (1 + r_B)^t$

$B_t = 3000 * (1 + 0.08)^t$

$B_t = 3000 * (1.08)^t$

The question requires that we solve for t when:

$A_t = B_t$

Where:

$A_t = A_0 * (1 + r_A)^t$

$A_t = 10000 * (1 + 3\%)^t$

$A_t = 10000 * (1 + 0.03)^t$

$A_t = 10000 * (1.03)^t$

and

$B_t = 3000 * (1.08)^t$

$A_t = B_t$ becomes

$10000 * (1.03)^t = 3000 * (1.08)^t$

Divide both sides by 10000

$(1.03)^t = 0.3 * (1.08)^t$

Divide both sides by $(1.08)^t$

$(\frac{1.03}{1.08})^t = 0.3$

$(0.9537)^t = 0.3$

Take natural logarithm of both sides

$\ln(0.9537)^t = \ln(0.3)$

Rewrite as:

$t\cdot\ln(0.9537) = \ln(0.3)$

Solve for t

$t = \frac{\ln(0.3)}{ln(0.9537)}$

$t = 25.397$

Approximate

$t = 25$

7 0

3 years ago

Yis inversely proportional tox.Wheny=50,x=4Work outywhenx=8

quester [9]

Answer:

55555

Step-by-step explanation:

8 0

3 years ago

The sector of a circle is shown below. It has a radius of 10 centimeters and a central

disa [49]

Answer:

1) 8.9 cm

2) 44.5 cm^2

Step-by-step explanation:

a) we want to calculate the length of the arc

Mathematically, we use the formula for the length of an arc

That will be ;

theta/360 * 2 * pi * r

theta = central angle = 51

r is radius = 10 cm

so we have ;

51/360 * 2 * 22/7 * 10 = 8.9 cm

2) The area of the sector is;

theta/360 * pi * r^2

51/360 * 22/7 * 10^2

= 44.5 cm^2

5 0

3 years ago

25 is what percent of 20?

denis-greek [22]

Answer:

20 is 80% of 25

Step-by-step explanation:

We assume, that the number 25 is 100% - because it's the output value of the task.

2. We assume, that x is the value we are looking for.

3. If 100% equals 25, so we can write it down as 100%=25.

4. We know, that x% equals 20 of the output value, so we can write it down as x%=20.

5. Now we have two simple equations:

1) 100%=25

2) x%=20

where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:

100%/x%=25/20

6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for 20 is what percent of 25

100%/x%=25/20

(100/x)*x=(25/20)*x - we multiply both sides of the equation by x

100=1.25*x - we divide both sides of the equation by (1.25) to get x

100/1.25=x

80=x

x=80

8 0

3 years ago

Read 2 more answers