What is the decay factor that corresponds to a product that decreases its value first by 20%, and than decreases by 40% of its value, and finally decreases by 62% of its value?

For each decrease, multiply by the fraction of the value that remains: a 20% decrease leaves 0.80, a 40% decrease leaves 0.60, and a 62% decrease leaves 0.38. The overall decay factor is 0.80 × 0.60 × 0.38 = 0.1824, so the correct choice is 0.1824.

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