Question

In a medical study, patients are classified in 8 ways according to whether they have

blood type AB+, AB−, A+, A−, B+, B− , O+, or O−, and also according to whether their

blood pressure is low, normal, or high. Find the number of ways in which a patient can

be classified.

Answer 1

The number of blood types $n_1=8,$ the number of blood pressure types $n_2=3,$

the total number of ways in which a patient can be classified

$N=n_1\cdot n_2=8\cdot3=24.$