A root is 6 cm long. It lengthens by 0.8 cm every day…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A root is long. It lengthens by every day.
- How long is it after days?
- After how many days is it long?
- What shape is the graph of its length against time, and which kind of growth is this?
Need a reminder? The key ideaShow
Arithmetic growth: , a straight line. Geometric growth: , a sigmoid curve with a lag, a log and a stationary phase. Absolute growth rate is the total gain in a unit of time. Relative growth rate is the gain per unit of the starting size. A part that doubles in a time has . Growth needs water, oxygen, nutrients and a suitable temperature.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Ten days. .
Step 2. Twenty-two cm. The root must gain . At a day this takes days.
Step 3. The graph. The same length is added each day, so the graph is a straight line. This is arithmetic growth.
Answer: ; days; a straight line, arithmetic growth.
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