Bunuel
At a San Diego Comic-Con, a total of 120 people attended either the DC panel, the Marvel panel, or both. How many people attended only the DC panel?
(1) 60% of the people who attended the DC panel also attended the Marvel panel.
(2) 75% of the people who attended the Marvel panel also attended the DC panel.
Gentle note to all experts and tutors: Please refrain from replying to this question until the Official Answer (OA) is revealed. Let students attempt to solve it first. You are all welcome to contribute posts after the OA is posted. Thank you all for your cooperation!The number of people who attended
Only DC = d
Only Marvell = m
Both = b
d + m+ b = 120
Statement 1 (1) 60% of the people who attended the DC panel also attended the Marvel panel.
\(\frac{6}{10}(d + b) = b\)
From this statement we will get a multiplicative relationship between d and b. However, to solve the equation we also need m. Hence, from Statement 1, we cannot find the value of d, b and m. Eliminate A, and D.
Statement 2 (2) 75% of the people who attended the Marvel panel also attended the DC panel.
\(\frac{3}{4}(m + b) = b\)
From this statement we will get a multiplicative relationship between m and b. However, to solve the equation we also need d. Hence, from Statement 2, we cannot find the value of d, b and m. Eliminate B.
CombinedCombined we have a relationship between d, b, and m. Hence, the equation d + m+ b = 120, has only one unknown which can be solved. Once we have one value, the others can also be derived throught the multiplicative relationship established in Statement 1, and Statement 2.
Option C