How do you convert a decimal to a percentage?

Multiply by 100, for example 0.35=35\%.

What is \frac13 as a recurring decimal?

0.\dot{3}, which is 33.\dot{3}\%.

What is the multiplier for a 12\% decrease?

0.88 (that is 100\%-12\%=88\%).

State the formula for percentage change.

\frac{change}{original}\times100

How do you share 56 in the ratio 3:5?

3+5=8 parts, one part =7, so the shares are 21 and 35.

What is the overall multiplier for +6\% then -4\%?

1.06\times0.96=1.0176, a 1.76\% rise (not 2\%).

Compound interest formula for r\% over n years?

amount\times\left(1+\frac{r}{100}\right)^n

How do you find the original price after a 20\% discount?

The sale price is 80\% of the original, so divide the sale price by 0.8.

What is the difference between a ratio and a rate?

A ratio compares quantities of the same kind; a rate compares quantities with different units (for example price per kg).

Why does a 12\% rise then a 12\% fall not return to the start?

Each percentage is taken from a different amount.

Fractions, decimals, percentages and ratioIB MYP Maths Standard: Flashcards

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Question

Write $\frac{3}{8}$ as a decimal and a percentage.

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Write $\frac{3}{8}$ as a decimal and a percentage.: $0.375$ and $37.5\%$ .
How do you convert a decimal to a percentage?: Multiply by $100$ , for example $0.35=35\%$ .
What is $\frac13$ as a recurring decimal?: $0.\dot{3}$ , which is $33.\dot{3}\%$ .
What is the multiplier for a $12\%$ increase?: $1.12$
What is the multiplier for a $12\%$ decrease?: $0.88$ (that is $100\%-12\%=88\%$ ).
State the formula for percentage change.: $\frac{\text{change}}{\text{original}}\times100$
How do you share $56$ in the ratio $3:5$ ?: $3+5=8$ parts, one part $=7$ , so the shares are $21$ and $35$ .
Simplify the ratio $1080:360$ .: Divide both by $360$ to get $3:1$ .
What is the overall multiplier for $+6\%$ then $-4\%$ ?: $1.06\times0.96=1.0176$ , a $1.76\%$ rise (not $2\%$ ).
Compound interest formula for $r\%$ over $n$ years?: $\text{amount}\times\left(1+\frac{r}{100}\right)^n$
How do you find the original price after a $20\%$ discount?: The sale price is $80\%$ of the original, so divide the sale price by $0.8$ .
What is the difference between a ratio and a rate?: A ratio compares quantities of the same kind; a rate compares quantities with different units (for example price per kg).
Why does a $12\%$ rise then a $12\%$ fall not return to the start?: Each percentage is taken from a different amount.

Exam questions on Fractions, decimals, percentages and ratio

In a survey at a school in Lagos, $\frac{7}{20}$ of the students walk to school and the rest travel by other means.
A total of $480$ students took part in the survey. Find how many of them do not walk to school.2 marks
A laptop has a price of $\$ 850$ before a sale.
The price of the laptop is $\$ 850 $before the sale. Find the overall percentage change from$ $850$ to the new price after the two changes. State whether it is an increase or a decrease.2 marks
A bicycle shop in Dubai sells a bicycle for AED $1440$ after a $20\%$ discount.
Find the original price of the bicycle.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).