Question

Out of 400 students to n the final year in a secondary school,300 are offering biology and 190 are offering chemistry
I.How many students are offering both biology and chemistry,if only 70 students are offering neither biology nor chemistry
ii.how many students are offering at least one of biology or chemistry

Answer 1

This is ideal for a Venn diagram solution.
In a rectangle representing the universal set of 400 students, draw
two intersecting circles labeled B and C
Label their intersection as x
label the "B only" as 300-x
labe the "C only" as 190-x
label the part outside the circle, but inside the rectangle as 70

300-x + x + 190-x + 70 = 400

i) solve or x
ii) that would clearly be 400-70 = ...

(curious to know where it is common to say "I am offering Biology" instead
of "I am taking Biology" ? )

Answer 2

Yes

Answer 3

Answer