Question

In a class of 50 students 30 study biology and 27 study chemistry .each students study at least one subject.1.illustrate the information on Venn diagram

Answer 1

Before you actually do that, it might be a good idea to do some
preliminary arithmetic.

let the number that study both be x

study only biology = 30-x
study only chemistry = 27-x

30-x + x + 27-x = 50
-x = -7
x = 7

then
study only biology = 23
study only chemistry = 20
study both = 7

now you can do your Venn diagram.