|
Interpreting the Answers
Trout
To estimate the number of trout in a reservoir, a gamekeeper
nets 100 fish, marks them and releases them. A few weeks later he
nets 200 and finds eight marked.
- What is his estimate of the number of trout?
- Why is his estimate not very reliable?
- How could he get a more reliable estimate?
Red Squirrels
To estimate the number of red squirrels in a wood, a warden
traps 10, marks them and releases them. A week later he traps
nine and finds five are marked.
- What is his estimate of the number of red
squirrels in the wood?
- How could he have made a more accurate estimate?
Suppose the warden set his traps in the same place each time.
- Do you think his estimate is likely to be too low
or too high? Why?
Grey Squirrels
Another warden tried to estimate the number of grey squirrels
in his wood. His first sample was 15 squirrels and his second was
20 squirrels, of which six were marked.
- What is his estimate of the number of the
squirrels in his wood?
Suppose that the two samples were taken in two successive
years.
- How should the warden change his estimate to make
it more accurate?
There are hunters in the area trying to catch squirrels.
- How should the warden change his estimate?
Whales
When marking whales, it is usual to fire a marker into the
side of the animal. It is possible that the marker might fall out
or that the people who capture the whale do not find the marker.
- How would this affect the estimates of the whale
population?
| 
