Percent Increase and Decrease: Practice

The change is $920 - 800 = 120$. Compare it to the original $800$.

$\frac{120}{800} \times 100\% = 0.15 \times 100\% = 15\%$

So the rent rose by $15\%$.

The size of the change is $250 - 210 = 40$. Compare it to the original $250$.

$\frac{40}{250} \times 100\% = 0.16 \times 100\% = 16\%$

So the population fell by $16\%$.

A $15\%$ increase uses the multiplier $1 + 0.15 = 1.15$.

$1.15 \times 340 = 391$

So the new value is $391$.

Tax is added, so multiply by $1 + 0.08 = 1.08$.

$1.08 \times 120 = 129.60$

The total is $129.60$ dollars.

First the discount: $30\%$ off leaves $70\%$, so $0.70 \times 90 = 63$. Then tax adds $5\%$ to that sale price.

$1.05 \times 63 = 66.15$

The final cost is $66.15$ dollars. The tax is figured on the discounted $63$, not the original $90$.

The change is $66 - 60 = 6$. Compare it to the original $60$.

$\frac{6}{60} \times 100\% = 0.10 \times 100\% = 10\%$

So this is a $10\%$ increase.

A $40\%$ discount leaves $60\%$, so $90$ is $60\%$ of the original. Divide the part by $0.60$.

$\frac{90}{0.60} = 150$

So the original price was $150$ dollars.

The change is $4{,}300 - 4{,}000 = 300$. Compare it to the original $4{,}000$.

$\frac{300}{4{,}000} \times 100\% = 0.075 \times 100\% = 7.5\%$

So the population rose by $7.5\%$.

The tip is $20\%$ of the menu price, so multiply.

$0.20 \times 35 = 7$

The tip is $7$ dollars. (The full bill would be $35 + 7 = 42$.)

A $36\%$ decrease leaves $64\%$, so multiply by $0.64$.

$0.64 \times 250 = 160$

So the new value is $160$.

The amount saved is the discount, which is $20\%$ of the original price.

$0.20 \times 250 = 50$

You save $50$ dollars, so the sale price is $250 - 50 = 200$.

The change is $46 - 40 = 6$. Compare it to the original $40$.

$\frac{6}{40} \times 100\% = 0.15 \times 100\% = 15\%$

So the value rose by $15\%$.