Among 150 faculty members in an institute, 55 are connected with each other through Facebook and 65 are connected throug...

Question

Among 150 faculty members in an institute, 55 are connected with each other through Facebook and 65 are connected through Whatsapp. 30 faculty members do not have Facebook or Whatsapp accounts. The number of faculty members connected only through Facebook accounts is:

A. 35
B. 45
C. 65
D. 90

Accepted Answer

35 faculty members use only Facebook. Answer: A. Out of 150 faculty, 30 have neither account. So 120 have at least one account. Using inclusion-exclusion we find those in both Facebook and Whatsapp, then subtract from the Facebook total to get Facebook-only members.

Among 150 faculty members in an institute, 55 are connected with each other through Facebook and 65 are connected through Whatsapp. 30 faculty members do not have Facebook or Whatsapp accounts. The number of faculty members connected only through Facebook accounts is: A. 35 B. 45 C. 65 D. 90