A jar holds 120 fruit flies. No flies are born, and none enter or leave…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A jar holds fruit flies. No flies are born, and none enter or leave. In the first week, flies die. Take the death rate of each week to be the same.
- What is the death rate for each fly in a week?
- How many flies are left after the first week?
- How many flies are left after three weeks? Give the answer to one decimal.
Need a reminder? The key ideaShow
A population changes by . The birth rate is and the death rate is for each individual in a stated time. The density can also be given as a biomass or a percent cover.
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.
Given. flies, deaths in a week, no births.
Plan. Find the death rate. Then multiply by the share that survives, once for each week.
Step 1. (a) for each fly in a week.
Step 2. (b) flies.
Step 3. (c) Each week, of the flies survive. flies.
Answer: ; ; flies.
Check. The number falls by a smaller amount each week, because the rate is for each fly and there are fewer flies.
Discussion (0)
Log in to join the discussion.
Loading…