Lesson 15: Finding This Percent of That

Find the value of each expression mentally.

$(0.23)  \boldcdot 100$

$50 \div 100$

$145 \boldcdot \frac{1}{100}$

$7 \div 100$

A school held several evening activities last month—a music concert, a basketball game, a drama play, and literacy night. The music concert was attended by 250 people. How many people came to each of the other activities?

During a sale, every item in a store is 80% of its regular price.

1. If the regular price of a T-shirt is $10, what is its sale price?
2. The regular prices of five items are shown here. Find the sale price of each item.

   		item 1	item 2	item 3	item 4	item 5
   row 1	regular price	$1	$4	$10	$55	$120
   row 2	sale price

3. You found 80% of many values. Was there a process you repeated over and over to find the sale prices? If so, describe it.

   

    

4. Which of the following expressions could be used to find 80% of $x$? Be prepared to explain your reasoning.

   $\frac{8}{100} \boldcdot x$

   $\frac{80}{100} \boldcdot x$

   $\frac{8}{10} \boldcdot x$

   $\frac{4}{10} \boldcdot x$

   $\frac85 \boldcdot x$

   $\frac45 \boldcdot x$

   $80 \boldcdot x$

   $8 \boldcdot x$

   $(0.8) \boldcdot x$

   $(0.08) \boldcdot x$