The graph shows the number of toys sold by a shop from March to June. In which 1-month interval was the percentage increase of toys sold the most? Answer : ___ to ___

1. Read the number of toys sold for each month from the graph

March: $20$
April: $40$
May: $50$
June: $80$

2. Calculate the percentage increase from March to April

Increase = $40 - 20 = 20$
Percentage increase = $\frac{20}{20} \times 100\% = 100\%$

3. Calculate the percentage increase from April to May

Increase = $50 - 40 = 10$
Percentage increase = $\frac{10}{40} \times 100\% = 25\%$

4. Calculate the percentage increase from May to June

Increase = $80 - 50 = 30$
Percentage increase = $\frac{30}{50} \times 100\% = 60\%$

5. Compare the percentage increases to find the largest

The percentage increases are $100\%$, $25\%$, and $60\%$.
The largest percentage increase is $100\%$, which occurred from March to April.