Results 1 to 6 of 6

- March 17th 2013, 08:59 PM #1

- Joined
- Mar 2013
- From
- va
- Posts
- 5

## Calculur problem help please

**Calculus question about tag and recapture?**

Here is the problem, i tried to do most of it but don't understand what its asking on c and d.

Tag and recapture is used to estimate populations of animals in the wild. First, sample of animals are captured, number=n. They are tagged and released back into the wild. Sometime later, another sample of animals are captured, number=s. Of the s animals in the second sample t are found to be tagged. The estimate of total animal N is ofund from N/n=s/t.

Supposed n=100, s=60, t=15. In the second sample 1/4 of the animals were tagged.

a) what is the total animal population based on these results.

i got 400

b) what is dN/dt of n=100 s=60 t=15

i got -26.67 idk what the negative is saying. i said N=ns/t and dN/dt= -st/t^2 i hope its right.

c) what is the differential change in N if one more animal had been captured in the second sample and it was found to be tagged. express your answer in whole animals. I dont really understand the equation so i dont know what to do.

i just substitued the 100 for n and 61 for s and 16 for t for the dN/dt= -st/t^2 equation and got -23.83

d) what is the the differential change in N if one more animal had been captured in the second sample and it was not found to be tagged. This is almost the same as c so i dont know.

Please help me atleast understand what c and d is asking. and how to start it.

- March 18th 2013, 06:00 AM #2

- Joined
- Mar 2013
- From
- BC, Canada
- Posts
- 104
- Thanks
- 17

## Re: Calculur problem help please

- March 18th 2013, 08:18 AM #3

- Joined
- Mar 2013
- From
- va
- Posts
- 5

- March 18th 2013, 09:08 AM #4

- Joined
- Mar 2013
- From
- BC, Canada
- Posts
- 104
- Thanks
- 17

## Re: Calculur problem help please

Well, gradient

*is*a direction and magnitude, a vector specifically, so your question is too vague stated in this way. A unit vector would give the direction as well as the original vector.

P.S. it's a bit rude not to be appreciate for the previous help if you're going to ask another question, and it would be best if you expressed this before moving on so abruptly. Just my opinion.

- March 18th 2013, 09:50 AM #5

- Joined
- Mar 2013
- From
- va
- Posts
- 5

## Re: Calculur problem help please

Im sorry good sir. I apologize. Thank you very much. I was i a hurry.

The second question states that there is function f(x y z) and point (x.y.z) and gradient is (20.30.15) and which dorection should i go to reach the point. I was little confused

- March 18th 2013, 10:23 AM #6

- Joined
- Apr 2005
- Posts
- 17,730
- Thanks
- 2271