Unit test

Google Classroom

Problem

Landen spent $L$L hours at the beach last weekend. Matéo spent $15\%$15, percent fewer hours at the beach than Landen did.

Which of the following expressions could represent how many hours Matéo spent at the beach last weekend?

Choose 2 answers:

Choose 2 answers:

• (Choice A, Incorrect)

  INCORRECT

  $L-\dfrac{1}{15}L$L, minus, start fraction, 1, divided by, 15, end fraction, L

  $15\%$15, percent means $15$15 per hundred, which we can write as $\dfrac{15}{100}$start fraction, 15, divided by, 100, end fraction and not as $\dfrac{1}{15}$start fraction, 1, divided by, 15, end fraction.
• (Choice B, Checked, Correct)

  CORRECT (SELECTED)

  $L(1-0.15)$L, left parenthesis, 1, minus, 0, point, 15, right parenthesis
• (Choice C, Incorrect)

  INCORRECT

  $0.15L$0, point, 15, L

  This is the difference in the number of hours that Landen and Matéo spent at the beach.
• (Choice D, Incorrect)

  INCORRECT

  $L-\dfrac{15}{100}$L, minus, start fraction, 15, divided by, 100, end fraction

  We can only subtract like units, so subtracting a rate from a number of hours would not be meaningful.
• (Choice E, Checked, Correct)

  CORRECT (SELECTED)

  $L-\dfrac{3}{20}L$L, minus, start fraction, 3, divided by, 20, end fraction, L

Hint #11 / 5

Landen spent $\maroonD{L}$start color #ca337c, L, end color #ca337c hours at the beach, and Matéo spent $15\%$15, percent fewer hours than Landen did.

So Matéo spent $\greenD{15\%\cdot L}$start color #1fab54, 15, percent, dot, L, end color #1fab54 fewer hours at the beach than Landen did.

Hint #22 / 5

That means Matéo spent $\maroonD{L}-\greenD{15\% \cdot L}$start color #ca337c, L, end color #ca337c, minus, start color #1fab54, 15, percent, dot, L, end color #1fab54 hours at the beach last weekend.

Hint #33 / 5

Because $15\%$15, percent means $15$15 per hundred, we can write it in equivalent forms.

$\begin{aligned} 15\%&=\dfrac{15}{100}\\\\ &=\dfrac{3}{20}\\\\ &=0.15 \end{aligned}$

Hint #44 / 5

Let's find equivalent ways of writing the number of hours Matéo spent at the beach last weekend.

$\begin{aligned} L-\blueD{15\%} \cdot L&=L-\blueD{\dfrac{3}{20}}L\\\\ &=L-\blueD{0.15}L\\\\ &=L(1-\blueD{0.15})\\\\ &=L(0.85) \end{aligned}$

Hint #55 / 5

The expressions $L(1-{0.15})$L, left parenthesis, 1, minus, 0, point, 15, right parenthesis and $L-{\dfrac{3}{20}}L$L, minus, start fraction, 3, divided by, 20, end fraction, L each could represent how many hours Matéo spent at the beach last weekend.