correct answer is: a) Class seven

Explanation

In class seven,
\rightarrow\frac{Number\ of\ Competetors}{Total\ Number\ of\ Students}
\rightarrow\large\frac{90}{150}
\rightarrow\large\frac{3}{5}
In class six,
\rightarrow\frac{Number\ of\ Competetors}{Total\ Number\ of\ Students}
\rightarrow\large\frac{80}{140}
\rightarrow\large\frac{4}{7}
Now, we get two fractions which are \large\frac{3}{5} and \large\frac{4}{7} .
We should find the LCM of the denominator.
So, The LCM of 5 and 7 is = 5\times7=35
Now,
\rightarrow\large\frac{3}{5}\normalsize=\large\frac{3\times7}{5\times7}\normalsize=\large\frac{21}{35}
\rightarrow\large\frac{4}{7}\normalsize=\large\frac{4\times5}{7\times5}\normalsize=\large\frac{20}{35}
\therefore\large\frac{21}{35}\normalsize>\large\frac{20}{35}
\therefore Class seven has the greater participation.
Ans: Class seven.

These precise math questions can also be expressed as:

1. In a sit and draw competition, 90 students from a total of 150 in class seven and 80 students from a total of 140 in class six took part. Which class had a greater number of participants?
2. From a pool of 150 students in class seven, 90 participated in a sit and draw competition, and from a pool of 140 students in class six, 80 participated. Which class demonstrated higher participation in the competition?
3. Among the students of class seven, 90 out of 150 participated in a sit and draw competition, while in class six, 80 out of 140 participated. Which class exhibited greater participation in the competition?