The results of oral health examination of grade one and grade six students in bright primary school are as follows: (1) Complete the following statistics according to the statistical information.

( 1);

(2) First grade:14 ÷ 52 ≈ 30%;

Sixth grade: 33 ÷ 58 ≈ 57%.

Answer: About 30% of the first-grade students have no dental caries, and about 57% of the sixth-grade students have no dental caries.