The graph shows the number of laptops sold from July to September last year. The total number of laptops sold in August and September was $\frac{2}{3}$ of the total number of laptops sold over the 3 months. The bar for the number of laptops sold in September has not been drawn. Complete the graph by shading to show the number of laptops sold in September. Ans:

1. Determine the fraction of laptops sold in July

Since August and September account for $\frac{2}{3}$ of the total, July accounts for $1 - \frac{2}{3} = \frac{1}{3}$ of the total.

2. Relate the fraction for July to the units on the graph

From the graph, July has 3 units. So, $\frac{1}{3}$ of the total is 3 units.

3. Calculate the total units for August and September

Since $\frac{1}{3}$ of the total is 3 units, $\frac{2}{3}$ of the total is $3 \times 2 = 6$ units. This is the total for August and September.

4. Determine the units for September

From the graph, August has 5 units. Therefore, September has $6 - 5 = 1$ unit.