Challenge  A jewelry box has the shape of a rectangular prism. Find the volume of the jewelry box. If the height is increased by 2 in.​, by how much does the volume​ increase?

7 and one half in.
8 and one fourth in.
4 and one half in.
         ​ (The figure is not to​ scale.)
Question content area bottom
Part 1
The volume of the jewelry box is
  
278 and seven sixteenths
in.cubed.
Part 2
The volume increases by
  
enter your response here in.cubed.

1 answer

To solve the problem, we'll first calculate the initial volume of the jewelry box using the formula for the volume of a rectangular prism:

\[ \text{Volume} = \text{length} \times \text{width} \times \text{height} \]

Assuming from your provided dimensions:

  • Height = \(4.5\) in = \( \frac{9}{2} \) in
  • Length = \(7.5\) in = \( \frac{15}{2} \) in
  • Width = \(8.25\) in = \( \frac{33}{4} \) in

Next, we compute the volume step-by-step:

  1. Convert height: \[ \text{Height} = 4.5, \text{in} = \frac{9}{2},\text{in} \]

  2. Convert length: \[ \text{Length} = 7.5, \text{in} = \frac{15}{2},\text{in} \]

  3. Convert width: \[ \text{Width} = 8.25, \text{in} = \frac{33}{4},\text{in} \]

Now let's compute the volume:

\[ \text{Volume} = \left( \frac{15}{2} \right) \times \left( \frac{33}{4} \right) \times \left( \frac{9}{2} \right) \]

Calculate step by step:

  • First, compute the product of \(15\), \(33\), and \(9\): \[ 15 \times 33 = 495 \]

    Then, \(495 \times 9 = 4455\)

  • Next, compute the product of the denominators: \[ 2 \times 4 \times 2 = 16 \]

Thus, the volume is: \[ \text{Volume} = \frac{4455}{16} \]

Now, let's convert this into a decimal or mixed number: \[ 4455 \div 16 = 278.4375 \text{ in}^3 \]

Converting \(278.4375\) to a mixed number gives: \[ 278 + \frac{7}{16} = 278 \frac{7}{16} \]

So, the volume of the jewelry box is confirmed as: \[ \text{Volume} = 278 \frac{7}{16} \text{ in}^3 \]

Part 2: Volume Increase When Height is Increased by 2 in

When the height is increased by 2 in, the new height becomes: \[ \text{New height} = 4.5 + 2 = 6.5, \text{in} \]

Now recalculate the volume with the new height: \[ \text{New Volume} = \left( \frac{15}{2} \right) \times \left( \frac{33}{4} \right) \times 6.5 \]

Convert \(6.5\) into a fraction: \[ 6.5 = \frac{13}{2} \]

Now calculate the new volume: \[ \text{New Volume} = \left( \frac{15}{2} \right) \times \left( \frac{33}{4} \right) \times \left( \frac{13}{2} \right) \]

Calculate the new product:

  • Numerator: \(15 \times 33 \times 13 = 15 \times 429 = 6435\)
  • Denominator: \(2 \times 4 \times 2 = 16\)

So: \[ \text{New Volume} = \frac{6435}{16} \]

Now calculating the new volume: \[ 6435 \div 16 = 402.1875 \text{ in}^3 = 402 \frac{3}{16} \]

Volume Increase:

Now find the increase in volume: \[ \text{Volume Increase} = \text{New Volume} - \text{Old Volume} = \frac{6435}{16} - \frac{4455}{16} = \frac{1980}{16} = 123.75 \text{ in}^3 \]

Expressed as mixed number: \[ 123.75 = 123 + \frac{3}{4} \]

So the volume increases by: \[ \text{Volume Increase} = 123 \frac{3}{4} \text{ in}^3 \]

Final Outputs:

  1. The volume of the jewelry box is \(278 \frac{7}{16} \text{ in}^3\).
  2. The volume increase is \(123 \frac{3}{4} \text{ in}^3\).