Answer
n($ P^{\prime}\cup$N )=90
(number of stocks that are either pharmaceutical, or have changed in value, or both)
Work Step by Step
P$\cup N^{\prime}$ is the set of stocks that are either pharmaceutical, or have changed in value, or both
Cardinality of union: n(P$\cup N^{\prime}$ )= n(P) +n($N^{\prime}$) -n(P$\cap$N')
n(P)= 50
n(N')=n(S)-n(N)=100- 40
n (P$\cap N^{\prime}$)= 10+10 (in column P, all that are not N)
n($ P^{\prime}\cup$N )=50+60-20=90
