Question 27: The school sets the target of the first semester for 7th grade students, which is the number of good, good, average, and weak students in the block with the ratio of 9,11,13,3 and no students. least. Know that the number of good students is 20 more than the number of good students. Choose the wrong sentence. Thus, according to school standards

Let the number of good, good, average, weak students in the block be: a;b;c;d(a,b,c,d∈N^*).

According to the topic we have:

\( \frac{a}{9} = \frac{b}{{11}} = \frac{c}{{13}} = \frac{d}{3} = \frac{{b – a} }{{11 – 9}} = \frac{{20}}{2} = 10\)

According to the properties of the series of equal ratios, we have:

\(\begin{array}{*{20}{l}} {\frac{a}{9} = 10 \Rightarrow a = 90}\\ {\frac{b}{{11}} = 10 \Rightarrow b = 110}\\ {\frac{c}{{13}} = 10 \Rightarrow c = 130}\\ {\frac{d}{3} = 10 \Rightarrow d = 30} \end{array}\ )

So:

The number of excellent students in the block is 90 students.

The number of good students in the block is 110 students.

The average number of students in the block is 130 students.

The number of weak students in the block is 30 students.

The answer to choose is: