A survey finds 840 bird species in a tropical forest region and 210 bird species in a region far to…
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A survey finds bird species in a tropical forest region and bird species in a region far to the north.
- How many times as many bird species does the tropical region have?
- How many more species does it have?
- By what per cent is the tropical number greater than the northern number?
Need a reminder? The key ideaShow
About 1.5 million species are described. Estimates of the total run from 7 million to 50 million. Animals are more than 70 per cent of the described species, plants are no more than 22 per cent, and insects are more than 70 per cent of the animals. The diversity is highest in the tropics and falls towards the poles.
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. (a) times as many.
Step 2. (b) more species.
Step 3. (c) per cent greater.
Answer: times; species; per cent.
Check. Four times as many is per cent more, not per cent more.
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