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eduard
3 years ago
6

Find the sum of the geometric series 1+ 0.8 + 0.8^2 + 0.8^3 + ... + 0.8^19

Mathematics
2 answers:
lubasha [3.4K]3 years ago
6 0
<h3>Answer: Approximately 4.94235392476964</h3>

Work Shown:

a = first term = 1

r = 0.8 = common ratio

We know the common ratio is 0.8 because we multiply this common ratio by each term to get the next term. The easiest to spot this is going from term1 to term2. Put another way, term2/term1 = 0.8/1 = 0.8 is our common ratio.

The general form of the nth term of a geometric sequence is a(r)^{n-1} and because the last term has an exponent of 19, this means n-1 = 19 solves to n = 20. Therefore, we are summing exactly n = 20 terms here.

Use the formula below to take a shortcut rather than painstakingly find all 20 terms and then summing them.

S = \frac{a*(1-r^n)}{1-r}\\\\S = \frac{1*(1-0.8^20)}{1-0.8}\\\\S \approx \frac{1*(1-0.01152921504607)}{1-0.8}\\\\S \approx \frac{1*(0.98847078495393)}{0.2}\\\\S \approx \frac{0.98847078495393}{0.2}\\\\S \approx 4.94235392476964\\\\

This value is approximate.

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

To check your answer, you could type the following into your calculator

1+0.8+0.8^2+0.8^3+0.8^4+0.8^5+0.8^6+0.8^7+0.8^8+0.8^9+0.8^10+0.8^11+0.8^12+0.8^13+0.8^14+0.8^15+0.8^16+0.8^17+0.8^18+0.8^19

Though as you can see, this is very tedious to type in. This is why the formula in the previous section above is preferred.

Oxana [17]3 years ago
3 0

Answer:idk I still trying to find it

Step-by-step explanation:

Sorry

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A coffee business sells a pound of coffee for $ 9.75. Monthly expenses are $ 4,500 plus $ 4.25 for every pound of coffee sold. a
hram777 [196]

Answer:

a. IT = 9.75 * X

b. GT = 4500 + 4.25 * X

c. G = 9.75 * X - 4500 - 4.25 * X

Step-by-step explanation:

With the data of the statement we can get a function. Let X be the number of pounds sold.

to. Monthly income

IT = 9.75 * X

b. Monthly expenses

GT = 4500 + 4.25 * X

c. Monthly Earnings (Monthly Income - Monthly Expenses)

G = 9.75 * X - (4500 + 4.25 * X)

G = 9.75 * X - 4500 - 4.25 * X

4 0
3 years ago
Find the payment necessary to amortize a 6.3% loan of 7500 compounded semiannually, with 6 semiannual payments. Find the payment
Lorico [155]

Answer:

Semiannual payment = $ 1391.37

Total payment = $ 8348.22

Interest paid =  $ 848.22

Step-by-step explanation:

Since, the semiannual payment formula of a loan,

P=\frac{PV(\frac{r}{2})}{1-(1+\frac{r}{2})^{-n}}

Where,

PV = present value of the loan,

n = number of semiannual payments,

r = annual rate,

Here, PV = 7500, r = 6.3% =0.063, n = 6,

By substituting the value,

The semiannual payment would be,

P=\frac{7500(\frac{0.063}{2})}{1-(1+\frac{0.063}{2})^{-6}}

\approx \$ 1391.37

Also, total payment = semiannual payment × total semiannual periods

= 1391.37 × 6

= $ 8348.22,

Also, the interest paid = total payment - present value

= 8348.22 - 7500

= $ 848.22

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3 years ago
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Ganezh [65]

Answer: The correct option is (D) pie.

Step-by-step explanation:  We are to select the correct number that produces an irrational number when multiplied by pie.

We know that if one of number is a non-zero rational number, then for the product to be irrational, we must have the other number irrational.

Give number is 2/5, which is rational. So the other number must be irrational.

Out of the given options, first three numbers are rational.

Only the last number pie is irrational. Because, the digits after the decimal are non-repeating and non-terminating.

So, the product will be irrational, if the other number is pie.

Thus, the correct option is (D).

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