EasyBiologyHigh School (11–12)Ecology and Environment › Organisms and PopulationsNumericalAPA-LevelIB
A town has 800 males and 760 females. How many females are there for every 1000 males? …
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A town has males and females.
- How many females are there for every males?
- What per cent of the town is female? Give the answer to one decimal.
- The ratio in another town is females for every males. What per cent of that town is female? Give the answer to one decimal.
Need a reminder? The key ideaShow
The sex ratio is the number of females for every males, . An age pyramid has a pre-reproductive, a reproductive and a post-reproductive group. A triangle means expanding, a bell means stable and an urn means declining.
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. males and females. Another town: females for every males.
Plan. Use the ratio, then the share of the whole.
Step 1. (a) .
Step 2. (b) .
Step 3. (c) In every people, are female. .
Answer: ; ; .
Check. A ratio below means that females are fewer than males, so their share is below .
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