The Australian Bureau of Meteorology uses the monthly air-pressure difference between Tahiti and Darwin, Australia, to calculate the Southern Oscillation Index:

SOI = 10(X – μ)/σ, where X is the air-pressure difference in the current month, μ is the average value of X for this month, and σ is the standard deviation of X for this month. Negative values of the SOI indicate an El Niño episode, which is usually accompanied by less than usual rainfall over eastern and northern Australia; positive values of the SOI indicate a La Niña episode, which is usually accompanied by more than usual rainfall over eastern and northern Australia. Suppose that X is normally distributed with a mean of μ and a standard deviation of σ. Explain why you believe that the probability of an SOI reading as low as –22.8, which occurred in 1994, is closer to 1.1 × 10⁻¹⁵, 0.011, or 0.110.