We need to take some samples from 2,697,460 image units to investigate (the minimum investigated unit is a TM image ) the total forest area of Heshun county in Shanxi province in year 2000, require that the absolute error isn't greater than 2 × 10 8 m² when significance level is less than 0.05. According to the previous investigated results, the standard deviation of the forest area of a TM image is approximately 380m² .

Objective:

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

Condition:

1. Significance level is 0.05;

2. The absolute error of the estimated total forest area isn't greater than 2 × 10 8 m² ;
   
3. The expected standard deviation of the forest area pixel is 380m² .

1. Optimal sample size, namely, the least pixel size to meet the requirement of sampling precision;
2. Distribute the samples, namely, extract the pixel number that need to be investigated from the sampling box by entire random way.
3. Calculate, namely, estimate the total forest area and sampling precision according to the sampling pixel and investigated data.