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amina.shaikh309
- Senior | Next Rank: 100 Posts
- Posts: 31
- Joined: Sat Apr 23, 2016 9:06 pm
Let's call the numbers a, b, and c, with a > b > c. We want to know if b = (a + b + c)/3, or if 2b = a + c.
S1:
a - c = 2*(a - b)
a - c = 2a - 2b
2b = a + c
Sufficient!
S2:
Suppose that (a + b + c) = 3a. Then b + c = 2a, but this is impossible! a > b and a > c.
Similarly, suppose that (a + b + c) = 3c. Then a + b = 2c, but this is impossible! a > c and b > c.
That leaves only one possibility: (a + b + c) = 3b, or a + c = 2b. Sufficient!
