Answer:
<h2>2 weeks.</h2>
Step-by-step explanation:
We can solve this problem by just using the given graph.
Notice that the straight line starts at , that means in week zero the beard was 10 millimeters long.
First, let's find the constant ratio of change, using two points (0,10) and (20,60)
According to the ratio, every 5 millimeter grows each 2 weeks, in other words, the ratio of growth is 2.5 millimeters per week.
Therefore, the right answer is 2 weeks.