For the example that gave the result (17), calculate approximately the probability that the fractional deviation from equilibrium /N1 is 1010 or larger. Take N1

For the example that gave the result (17), calculate approximately the probability that the fractional deviation from equilibrium δ/N1 is 10–10 or larger. Take N1 = N2 = 1022. You will find it conversion to use an asymptotic expansion for the complementary error function. When x >> 1,

2xexp(x2)∫∞xexp (–l2) dt ≈ 1 + small terms.