Description:

We need to take some samples from 2,697,460 image units to investigate (the minimum investigated unit is A TM image ) the area of forest coverage of Heshun county in Shanxi province in year 2000, require that the total estimated cost isn't greater than 200,000 yuan , standard deviation and investigation cost of each layer unit can be estimated according to the previous investigation experience, the base cost of estimation is approximately 8000 yuan, the average investigation cost of each pixel is 120 yuan.

Sampling method:

Sandwich sampling

Sampling box: All pixels of TM images of Heshun county in Shanxi province in July 1,2000

Objective:

To estimate the forest area of Heshun county in year 2000 by sampling

Condition:

1. The total cost is 200,000 yuan;
2. The base cost is 8000 yuan （ This cost is the fixed cost that is irrelevant to the sample size, include organization 、 propaganda 、 design of the questionnaire and the necessary device, and so on ） ;
3. The average investigation cost of each pixel (sample unit) is 120 yuan;
4. According to the experience, standard deviation （ Standard deviation is the root of the mean of sum of squares of deviations, which reflects the dispersion degree of this layer ） and investigation cost in each layer can be estimated as follows:

Request:

1. Total optimal sample size and sample size of each knowledge layer
   
2. Distribute the samples;
3. Calculate, namely, estimate the total forest area and sampling accuracy according to the sampling pixel and investigated data..