μ = 3/5 = 0.6; σ = 1/10 = 0.1

2/5 = 0.4 = 0.6 - 0.2 = 0.6 - (2 x 0.1) = μ - 2σ

1 = 0.6 + 0.4 = 0.6 + (4 x 0.1) = μ + 4σ

The value (2/5) is two (2) standard deviations below the mean, and 1 is four (4) standard deviations above the mean. We would expect 97.5% (i.e. 34% + 13.5% + 50%) probability of a value occurring between 2/5 and 1. This probability is between is between 50% and 100% and therefore a value within the given range would be very likely.