Answer: C. 74
Step-by-step explanation:
Let M= Number of workers are in marketing team .
S = Number of workers are in Sales team.
V = Number of workers are in Vision team.
As per given , we have
n(M) = 20 , n(S) = 30 , n(V) = 40
n(M∩S) = 5 , n(V∩S) = 6 , n(M∩V) = 9
n(M∩S∩V) =4
Using formula of sets , we get
n(M∪S∪V) =n(M)+n(S) +n(V) -n(M∩S) - n(V∩S)-n(M∩V) +n(M∩S∩V)
Substitute the corresponding values , we get
n(M∪S∪V) =20+30+40-5-6-9 +4
= 74
∴ The number of workers are in at least one team = 74
Therefore , the total number of workers =74
Hence, the correct option is : C. 74
