Bunuel wrote:
In the last month Super Tele-Com has offered flat-rate service packages on landline telephones, cellular phones and DSL high speed internet to a select group of long-time customers in a particular city. Of this group thirty percent opted to sign up for only one of the three flat-rate packages. While no customers opted to just take flat-rate cell phone and DSL service, 65 people decided to sign up for only flat-rate land line service and one other flat-rate service. If 330 people signed up for some form of flat-rate service, how many people opted to sign up for all three packages?
A. 166
B. 140
C. 98
D. 77
E. 65
We can create the following equation:
# of people who signed up = # signed up for 1 package + # signed up for 2 packages + # signed up for 3 packages + # signed up for 0 packages
Since 30 percent of the 330 people signed up for only one package, we can say:
# signed up for 1 package = 0.3 x 330 = 99
Since no customers opted to just take flat-rate cell phone and DSL service and 65 people decided to sign up for only flat-rate landline service and one other flat-rate service, we can say:
# signed up for 2 packages = 65
Since all 330 people signed up for some form of flat-rate service, we can say:
# signed up for 0 packages = 0
Finally we can let T = # signed up for 3 packages and create the following equation to determine T:
330 = 0.3(330) + 65 + T + 0
330 = 99 + 65 + T
330 = 164 + T
166 = T
Answer: A