Percentage increase and decrease questions with answers

Questions

1. Question 1Increase a quantity by a percentage

   Increase $360$ by $10\%$.

   Show the worked solution

   1. Step 1: Write the new value as a percentage of the original$100\% + 10\% = 110\%$
   2. Step 2: Multiply the original value by this percentage$\text{New value} = \dfrac{110}{100} \times 360$$= 396$
2. Question 2Decrease a quantity by a percentage

   A bicycle cost $800 last year. Its price has fallen by 10%. Find its price now.

   Show the worked solution

   1. Step 1: Write the new value as a percentage of the original$100\% - 10\% = 90\%$
   2. Step 2: Multiply the original value by this percentage$\text{New value} = \dfrac{90}{100} \times 800$$= 720$Its price now is $720.
3. Question 3Find the percentage increase

   A family's monthly electricity bill rose from $160 to $200. Find the percentage increase.

   Show the worked solution

   1. Step 1: Find the increase$\text{Increase} = 200 - 160$$\phantom{\text{Increase}} = 40$
   2. Step 2: Percentage increase: divide by which value, then multiply by 100%?$\text{Percentage increase} = \dfrac{40}{160} \times 100\%$$= 25\%$
4. Question 4Find the percentage decrease

   The number of members of a sports club went down from 1,200 to 1,140. Find the percentage decrease in the number of members.

   Show the worked solution

   1. Step 1: Find the decrease$\text{Decrease} = 1200 - 1140$$\phantom{\text{Decrease}} = 60$
   2. Step 2: Percentage decrease: divide by which value, then multiply by 100%?$\text{Percentage decrease} = \dfrac{60}{1200} \times 100\%$$= 5\%$