1.

Three numbers a, b and c are chosen at random (simultaneously) from among the numbers 1, 2, 3, ..., 99. The probability that a3 + b3 + c3 - 3abc is divisible by 3, is

A. \(\rm\frac{3\times {^{33}C_3}+ \left(^{33}C_1\right)^3}{^{99}C_3}\)
B. \(\rm\frac{3\times {^{33}C_3}- \left(^{33}C_1\right)^3}{^{99}C_3}\)
C. \(\rm\frac{2\times {^{33}C_3}+ \left(^{33}C_1\right)^3}{^{99}C_3}\)
D. \(\rm \frac{2\times {^{33}C_3}-\left(^{33}C_1\right)^3}{^{99}C_3}\)
Answer» B. \(\rm\frac{3\times {^{33}C_3}- \left(^{33}C_1\right)^3}{^{99}C_3}\)


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