There are 20000 people living in defence colony, gurgaon. Out of them 9000 subscribe to star Tv network and 12000 to zee TV network. If 4000 subscribe to both, how many do not subscribe to any of the two? 

Correct option is A

• Total population = 20,000

• Subscribers of Star TV = 9,000

• Subscribers of Zee TV = 12,000

• Subscribers of both = 4,000

Using the formula for union of two sets:

∣A∪B∣=∣A∣+∣B∣−∣A∩B∣ 

∣A∪B∣ =9,000+12,000−4,000=17,000

People subscribing to at least one network = 17,000.
People not subscribing to any = Total population - Subscribers = 20,000−17,000 = 3,000

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