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2 years ago

9. If y = 30 when x = 7, find x when y = 12.

Mathematics

1 answer:

Marianna [84]2 years ago

6 0

I have my work at the bottom but to explain you have to divide 30/12, and I got 2.5. That means 30 is 2.5 times bigger than 12. Because we have to find x, we have to divide 7/2.5, to find what is 2.5 times smaller than 7. That’s 2.8. So, x= 2.8

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lina2011 [118]

$\bf \qquad \qquad \textit{Future Value of an ordinary annuity}\\
\left. \qquad \qquad \right.(\textit{payments at the end of the period})
\\\\
A=pymnt\left[ \cfrac{\left( 1+\frac{r}{n} \right)^{nt}-1}{\frac{r}{n}} \right]$

$\bf \qquad 
\begin{cases}
A=
\begin{array}{llll}
\textit{accumulated amount}\\
\end{array}\to &
\begin{array}{llll}
8000
\end{array}\\
pymnt=\textit{periodic payments}\\
r=rate\to 5\%\to \frac{5}{100}\to &0.05\\
n=
\begin{array}{llll}
\textit{times it compounds per year}\\
\textit{monthly, thus twelve}
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\end{cases}$

$\bf 8000=pymnt\left[ \cfrac{\left( 1+\frac{0.05}{12} \right)^{12\cdot 4}-1}{\frac{0.05}{12}} \right]
\\\\\\
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6 0

2 years ago

Use the diagram below to solve for x and y. Please help! Fast if possible.

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Answer:

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Step-by-step explanation:

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2 years ago

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2 years ago

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3 0

2 years ago

Donald is 38 years younger than Natalie. 5 years ago, Natalie's age was 3 times Donald's age. How old is Donald now?

Svetlanka [38]

9514 1404 393

Answer:

Step-by-step explanation:

Let d represent Donald's age now. Then Natali's age now is d+38. The age relationship 5 years ago was ...

(d+38) -5 = 3(d -5)

d +33 = 3d -15 . . . . . eliminate parentheses

48 = 2d . . . . . . . . . . . add 15-d

24 = d . . . . . . . . . . . . . divide by 2

Donald is 24 years old now.

_____

<em>Alternate solution</em>

You can also work this by considering that 5 years ago, Natalie's age was more than Donald's age by twice Donald's age then. Hence Donald was 38/2 = 19 at that time. Now, Donald is 19+5 = 24.

4 0

2 years ago

9. If y = 30 when x = 7, find x when y = 12.​

9. If y = 30 when x = 7, find x when y = 12.