Helppp please!!! with the equation, i have no clue

An author published a book which was being sold online. The first month the author sold 21000 books, but the sales were declinin

Wittaler [7]

Answer: 119,616

You may have to erase the comma when inputting the answer.

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Explanation:

The author sells 21,000 books in the first month.

Then they sell 21,000*(1-0.12) = 21,000*(0.88) = 18,480 in the second month.

Then they sell 18,480*(1-0.12) = 18,480*(0.88) = 16,262.4 = 16,262 in the third month.

And so on. These values follow a geometric sequence with first term a = 21,000 and common ratio r = 0.88

We can think of the 0.88 as 88% of the original value (since losing 12%, we keep the remaining 88%)

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Use the formula below to sum the first 9 terms of the geometric sequence

Plug in a = 21000 and r = 0.88

$S_n = a*\frac{1-r^n}{1-r}\\\\S_9 = 21000*\frac{1-0.88^9}{1-0.88}\\\\S_9 \approx 21000*\frac{0.6835216}{0.12}\\\\S_9 \approx 21000*5.6960133\\\\S_9 \approx 119,616.2793\\\\S_9 \approx 119,616\\\\$

The author sold about 119,616 books over the course of the first nine months.

4 0

3 years ago

If x = -6 and y = -2, evaluate the expression. 3x - 10 y-5

Bond [772]

Is it
3x-10= 3(-6)-10= -28
Y-5= -2-5=-7

3 0

2 years ago

A coffee company wants to make sure that their coffee is being served at the right temperature. If it is too hot, the customers

Cerrena [4.2K]

Answer:

Null hypothesis: $\mu = 65$

Alternative hypothesis: $\mu \neq 65$

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

For this case the value of $\mu$ represent the parameter associated to the population (True average of cofee temperature)

Step-by-step explanation:

Data given and notation

$\bar X=70.2$ represent the mean height for the sample

$s$ represent the sample standard deviation for the sample

$n=20$ sample size

$\mu_o =765$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the true mean i equal to 70.2, the system of hypothesis would be:

Null hypothesis: $\mu = 65$

Alternative hypothesis: $\mu \neq 65$

If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

For this case the value of $\mu$ represent the parameter associated to the population (True average of cofee temperature)

3 0

3 years ago

Find the indicated side of the right triangle. 45° y 6 45°

Pavlova-9 [17]

Answer:

6

Step-by-step explanation:

tan 45 = 6 / x

1 = 6 / x

x = 6

Note :

Tan 45 value = 1

7 0

3 years ago

Read 2 more answers

wind and weather patterns are caused when warm air near the surface of the earth rises to higher levels in the atmosphere the ai

wolverine [178]

I believe that is convection

6 0

3 years ago