Question

Of the students who tool English in a certain school one year, 60% of them took History, 30% of them took Biology, and 10% took both History and Biology.

One of the students is chosen at random.
a) Find the probability that the student took neither History nor Biology
b) Given that the student took exactly one of History and Biology, find the probability it was History

Answer 1

see below

Explanation:

Easiest way to do this is to draw a Venn diagram (see attached)

a) 0.2 = 20%

b) 0.5 = 50%