Tahmar knows the formula for simple interest is I = Prt, where I represents the simple interest on an amount of money, P, for t years at r rate. She transforms the equation to isolate P : P = P : P equals StartFraction I Over r t EndFraction.. Using this formula, what is the amount of money, P, that will generate $20 at a 5% interest rate over 5 years?

11 answers

To find the amount of money \( P \) that will generate $20 at a 5% interest rate over 5 years, we can use the formula for simple interest, which is \( I = Prt \).

We want to isolate \( P \), so we rearrange the formula:

\[ P = \frac{I}{rt} \]

Here, \( I \) represents the simple interest ($20), \( r \) is the interest rate (5% or 0.05 in decimal), and \( t \) is the time period in years (5 years).

Now we can plug in the values:

  • \( I = 20 \)
  • \( r = 0.05 \)
  • \( t = 5 \)

Now substituting these values into the formula gives:

\[ P = \frac{20}{0.05 \times 5} \]

Calculating the denominator:

\[ 0.05 \times 5 = 0.25 \]

Now substituting back into the equation:

\[ P = \frac{20}{0.25} \]

Calculating that gives:

\[ P = 80 \]

Thus, the amount of money \( P \) that will generate $20 at a 5% interest rate over 5 years is $80.

The tax rate as a percent, r, charged on an item can be determined using the formula StartFraction c Over p EndFraction minus 1 equals r. – 1 = r, where c is the final cost of the item and p is the price of the item before tax. Louise rewrites the equation to solve for the final cost of the item: c = p(1 + ). What is the final cost of a $40 item after an 8% tax is applied?

To find the final cost of a $40 item after an 8% tax is applied, we can use the formula you provided. First, let's clarify the formula for the final cost \( c \):

\[ c = p(1 + r) \]

where:

  • \( p \) is the price of the item before tax,
  • \( r \) is the tax rate expressed as a decimal.

Given:

  • \( p = 40 \)
  • \( r = 8% = 0.08 \)

Now, substituting these values into the formula:

\[ c = 40(1 + 0.08) \]

Calculating the expression in parentheses:

\[ 1 + 0.08 = 1.08 \]

Now, substitute this back into the equation:

\[ c = 40 \times 1.08 \]

Calculating that gives:

\[ c = 43.20 \]

Therefore, the final cost of a $40 item after an 8% tax is applied is $43.20.

The equation f = v + at represents the final velocity of an object, f, with an initial velocity, v, and an acceleration rate, a, over time, t. Which is an equivalent equation solved for a?

StartFraction f minus v Over t EndFraction equals a. = a
StartFraction f Over t EndFraction plus v equals a.– v = a
StartFraction f plus v Over t EndFraction equals a. = a
StartFraction f Over t EndFraction plus v equals a.+ v = a

To isolate \( a \) in the equation \( f = v + at \), we can follow these steps:

  1. Subtract \( v \) from both sides to move the initial velocity term to the left side:

    \[ f - v = at \]

  2. Next, divide both sides by \( t \) to solve for \( a\):

    \[ a = \frac{f - v}{t} \]

So, the equivalent equation solved for \( a \) is:

\[ a = \frac{f - v}{t} \]

This matches the first option you provided:

\[ \frac{f - v}{t} = a \]

Thus, the correct answer is:

StartFraction f minus v Over t EndFraction equals a. = a.

The equation a = StartFraction one-half EndFraction left-parenthesis b 1 plus b 1 right-parenthesis.(b1 + b2)h can be used to determine the area, a, of a trapezoid with height, h, and base lengths, b1 and b2. Which are equivalent equations? Check all that apply.

StartFraction 2 a Over h EndFraction minus b 2 equals b 1.– b2 = b1
StartFraction a Over 2 h EndFraction minus b 2 equals b 1. – b2 = b1
StartFraction 2 a minus b 2 Over h EndFraction equals b. = b1
StartFraction 2 a Over b 1 plus b 2 EndFraction equals h. = h
StartFraction a Over 2 left-parenthesis b 1 plus b 1 right-parenthesis EndFraction equals h.= h

To determine which of the equations provided are equivalent to the original equation \( a = \frac{1}{2}(b_1 + b_2)h \), we can manipulate the original equation and see how these options relate to it.

Starting with the formula:

\[ a = \frac{1}{2}(b_1 + b_2)h \]

Rearranging for \( b_1 \):

We can isolate \( b_1 \):

  1. Multiply both sides by \( 2 \):

    \[ 2a = (b_1 + b_2)h \]

  2. Now, divide both sides by \( h \):

    \[ \frac{2a}{h} = b_1 + b_2 \]

  3. Finally, isolate \( b_1 \):

    \[ b_1 = \frac{2a}{h} - b_2 \]

This means the equation \( \frac{2a}{h} - b_2 = b_1 \) is equivalent.

Rearranging for \( h \):

Let's also rearrange for \( h \):

Starting from:

\[ 2a = (b_1 + b_2)h \]

  1. Divide both sides by \( (b_1 + b_2) \):

    \[ h = \frac{2a}{b_1 + b_2} \]

This shows that the equation \( \frac{2a}{b_1 + b_2} = h \) is also equivalent.

Evaluating the Options:

Now let's check each of the provided options:

  1. \( \frac{2a}{h} - b_2 = b_1 \): This is equivalent.
  2. \( \frac{a}{2h} - b_2 = b_1 \): This is not equivalent (does not match the steps).
  3. \( \frac{2a - b_2}{h} = b_1 \): This is also not equivalent.
  4. \( \frac{2a}{b_1 + b_2} = h \): This is equivalent.
  5. \( \frac{a}{2(b_1 + b_1)} = h \): This is not equivalent (there's a typo in the equation as \( b_1 + b_1 \) should be \( b_1 + b_2 \)).

Summary of Equivalent Equations:

  • \( \frac{2a}{h} - b_2 = b_1 \) (Equivalent)
  • \( \frac{2a}{b_1 + b_2} = h \) (Equivalent)

The equivalent equations are options 1 and 4.

Nathaniel writes the general form of the equation gm = cm + rg for when the equation is solved for m. He uses the general form to solve the equation –3m = 4m – 15 for m. Which expression shows what Nathaniel will actually evaluate?

4 + 15 – 3
4 – 15 + 3
StartFraction negative 15 Over negative 3 minus 4 EndFraction.
–15 – negative 15 minus StartFraction negative 3 Over 4 EndFraction.

To solve the equation \(-3m = 4m - 15\) for \(m\), let's first rearrange it to isolate \(m\).

  1. Start with the original equation: \[ -3m = 4m - 15 \]

  2. Add \(3m\) to both sides to move all terms involving \(m\) to one side: \[ 0 = 4m + 3m - 15 \quad \Rightarrow \quad 0 = 7m - 15 \]

  3. Next, add \(15\) to both sides to isolate the \(m\) term: \[ 15 = 7m \]

  4. Finally, divide both sides by \(7\) to solve for \(m\): \[ m = \frac{15}{7} \]

Now, let's express this process using the expressions provided to evaluate.

From our rearrangement, we reached \(m = \frac{15}{7}\), or we could work it out as follows to see which expression corresponds to our working:

Starting from \(0 = 7m - 15\), if we were to rearrange it as \(7m = 15\), we could divide:

To find an equivalent form for \(m = \frac{15}{7}\), we could also illustrate the steps from rearranging:

The equation could also be illustrated as:

  • Adding \(15\) to both sides, we have: \[ 4m + 15 = 3m \]

However, looking at the expressions provided:

  1. \(4 + 15 - 3\): This does not match our rearrangement process.
  2. \(4 - 15 + 3\): This does not match our rearrangement process.
  3. \(\frac{-15}{-3 - 4}\): This could be viewed as \(-15\) divided by \(-7\), and simplifies to \(m = \frac{15}{7}\) which holds. (Equivalent)
  4. \(-15 - (-15) - \frac{-3}{4}\): This does not match our rearrangement process.

Thus, the expression that Nathaniel will actually evaluate, based on the transformation to solve \(m\), is:

\(\frac{-15}{-3 - 4}\).

-15/-3-4

Let's analyze the expression \(-15 / -3 - 4\) step by step.

  1. Evaluate \(-15 / -3\): \[ -15 / -3 = 5 \]

  2. Subtract \(4\) from that result: \[ 5 - 4 = 1 \]

So, the final result is: \[ -15 / -3 - 4 = 1 \]

If we were to relate this back to solving the equation \(-3m = 4m - 15\):

From our earlier solution, we found that:

  • The solution for \(m\) is derived from setting up the equation to isolate \(m\) which led to: \[ 7m = 15 \implies m = \frac{15}{7} \]

However, the evaluation of the expression \(-15 / -3 - 4\) yields a final result of 1. If you are looking to relate this back to equation manipulation regarding \(m\) as a comparison to find \(m\), remember from the original rearrangement \(7m = 15\) simplifying to \(m = \frac{15}{7}\), reflects another direction entirely.

Let me know if you need any further insights or clarifications!