Question

in a class of final year student in a school, 350 offer chemistry and 200 offer physics. if 90 student offer neither chemistry nor physics;

i: how many students are offering both subject.

ii: how many students are offering only one subject.

iii: how many students are offering at least one subject

Answer 1

Out of 500 students in a final year of a senior secondary, 350 offer chemistry and 200 offer physics.

i. Let $x=$ the number of students offering both subjects

Then

$$500=x+350-x+200-x+90$$

$$x=140$$

140 students are offering both subjects.

ii.

$$350-140=210$$

$$200-140=60$$

$$210+60=270$$

270 students are offering only one subject.

iii.

$$500-90=410$$

410 students are offering at least one subject.