Official Solution:If out of 200 programmers, 30% are familiar with Python, 80% with JavaScript, and 10% do not have proficiency in either of these programming languages, how many ways can a team of three programmers, all proficient in both Python and JavaScript, be formed? A. 2960
B. 3990
C. 6840
D. 8820
E. 9880
Total = Python + JavaScript - Both + Neither.
• If 30% are familiar with Python, then Python \(= 0.3*200 = 60\).
• If 80% are familiar with JavaScript, then JavaScript \(= 0.8*200 = 160\).
• If 10% are not proficient in either language, then Neither \(= 0.1*200 = 20\).
Substituting these values into the equation, we get \(200 = 60 + 160 - Both + 20\), which implies Both \(= 40\).
The number of different teams of 3 that can be formed from these 40 programmers is given by \(C^3_{40} = \frac{40!}{3!*37!} = \frac{38*39*40}{2*3} = 19*13*40 = 9880\).
Answer: E