Estimating Percentages

Lesson

A lot of the time it's hard for us to accurately calculate percentages of amounts in real life, so we'll have to estimate! Because percentages are expressed as something out of a hundred, we can also express them in diagrams of $5,10,100$5,10,100 things or more!

Now it's your turn!

Example

Someone has been eating the brand new $10\times10$10×10 square block of chocolate! Can you figure out how much of the original chocolate block is left in percentages?

Think about the chocolate block as a fraction first

Do :We can see that there used to $10\times10=100$10×10=100 blocks of chocolate here, and now there are $67$67 blocks. So the fraction that represents how much is left of the original is $\frac{67}{100}$67100 . This is easily translated into a percentage as the denominator is already $100$100 , so the answer is $67%$67% .

Worked Examples

QUESTION 1

Which point on the line is closest to $56%$56%?

$A$A
A
$C$C
B
$D$D
C
$B$B
D

QUESTION 2

$Ellie$ bought a $454$454 mL drink that claimed to be orange juice. In the ingredients list it said that orange juice made up $17%$17% of the drink. To estimate the amount of orange juice in the drink, which of the following would give the closest answer?

$10%\times454$10%×454
A
$20%\times454$20%×454
B
$10%\times400$10%×400
C

QUESTION 3

In a census, people are asked their gender and age. The graph shows the results: the percentage of females and males in each age group.

To the nearest $1%$1%, what percentage of females are between $5$5 and $9$9 years of age?
$7%$7%
A
$2%$2%
B
$11%$11%
C
To the nearest $1%$1%, what percentage of males are between $30$30 and $34$34 years of age?
$7%$7%
A
$4%$4%
B
$2%$2%
C
The percentage of females between the ages of $20$20 and $29$29 is about:
$15%$15%
A
$7%$7%
B
$25%$25%
C
The percentage of males below $20$20 years of age is about:
$15%$15%
A
$10%$10%
B
$30%$30%
C
$50%$50%
D