Hello there when i looked for an answer on your site i found it but it was wrong

Use the "rule of 72" to estimate the doubling time (in years) for the interest rate, and then calculate it exactly. (Round your

bonufazy [111]

Answer:

Using the rule of 72, the doubling time is 9.35 years.

The exact answer is that the doubling time is 8.89 years.

Step-by-step explanation:

By the rule of 72, we have that the doubling time D is given by:

$D = \frac{72}{Interest Rate}$

The interest rate is in %.

In our exercise, the interest rate is 7.7%. So, by the rule of 72:

$D = \frac{72}{7.7} = 9.35$ .

Exact answer:

The exact answer is going to be found using the compound interest formula(since the rule of 72 is a simplification of this formula).

The compound interest formula is given by:

$A = P(1 + \frac{r}{n})^{nt}$

Where A is the amount of money, P is the principal(the initial sum of money), r is the interest rate(as a decimal value), n is the number of times that interest is compounded per unit t and t is the time the money is invested or borrowed for.

So, for this exercise, we have:

We want to find the doubling time, that is, the time in which the amount is double the initial amount, double the principal.

$A = 2P$

$r = 0.077$

There are 52 weeks in a year, so $n = 52$

$A = P(1 + \frac{r}{n})^{nt}$

$2P = P(1 + \frac{0.077}{52})^{52t}$

$2 = (1.0015)^{52t}$

Now, we apply the following log propriety:

$\log_{a} a^{n} = n$

So:

$\log_{1.0015}(1.0015)^{52t} = \log_{1.0015} 2$

$52t = 462.44$

$t = \frac{462.44}{52}$

$t = 8.89$

The exact answer is that the doubling time is 8.89 years.

6 0

3 years ago

Two brothers, Mark and Walter, each inherit $20000. Mark invests his inheritance in a savings account with an annual return of 2

Igoryamba

Answer:

$720

Step-by-step explanation:

$20000 - 100%

$x. - 2.5%

x=(20000*2.5)/100=500

20000+500=$20500 in one year (Mark)

20000 - 100

x. - 6.1

x= (20000*6.1)/100 = 1220

20000+1220= $21220 (Walter)

21220-20500= $720 more (Walter will have after 1 year)

3 0

2 years ago

Help I don’t understand the concept

kvasek [131]

Answer:

C. No, because one x-value corresponds to two different y-values

Step-by-step explanation:

An x-value cannot have two y-values. Hope this helps!

6 0

2 years ago

Read 2 more answers

What property describe the number sentence 6 plus 0 equal 6

nata0808 [166]

The identity property of addition states that any number plus zero equals the original number. So, 6 + 0 = 6 shows the identity property of addition. Other number sentences that show this property would include: 8 + 0 = 8, 153 + 0 = 153, and 1,899,888 + 0 = 1,899,888. In each case, the original number plus 0 equals the original number. It doesn't matter how large or small the original number is.

8 0

3 years ago

Choose the most appropriate strategy and then use it to solve the quadratic equation.

dsp73

(x-8) ^ 2 = 121
(x-8) = + / - root (121)
x = 8 +/- root (121)
The solutions are:
x1 = 8 + root (121)
x2 = 8 - root (121)
2a ^ 2 = 8a-6
2a ^ 2-8a + 6 = 0
a ^ 2-4a + 3 = 0
(a-1) (a-3) = 0
The solutions are:
a1 = 1
a2 = 3
x ^ 2 + 12x + 36 = 4
x ^ 2 + 12x + 36-4 = 0
x ^ 2 + 12x + 32 = 0
(x + 4) (x + 8) = 0
The solutions are:
x1 = -8
x2 = -4
x ^ 2-x + 30 = 0
x = (- b +/- root (b ^ 2 - 4 * a * c)) / 2 * a
x = (- (- 1) +/- root ((- 1) ^ 2 - 4 * (1) * (30))) / 2 * (1)
x = (1 +/- root (1 - 120))) / 2
x = (1 +/- root (-119))) / 2
x = (1 +/- root (119) * i)) / 2
The solutions are:
x1 = (1 + root (119) * i)) / 2
x2 = (1 - root (119) * i)) / 2

7 0

3 years ago