(1) In real life, we often need to use percentages for statistics. The product qualification rate indicates the percentage of (qualified products) in (produced products); The attendance of students shows the percentage (of all students).

(2) Soybean oil yield is oil production quality/soybean quality * 100%. The qualified rate of products is (number of qualified products)/(number of produced products) * 100%.

2. Three students, A, B and C, took part in a 20-question oral arithmetic contest. The result is that A is right 18, B is all right, and C is wrong. First find the correct rate of each population calculation.

A: 18/20* 100%=90%,

B: 20/20*%= 100%，

c:(20- 1)/20 * 100% = 95%，

The ranking of the competition is B, C and A. ..

Class 6 (1) has thirty-eight people here today, and two of them are absent due to special circumstances. Find today's attendance and absence.

38/40* 100%=95%,

Absence rate is 1-95%=5%.