Respuesta :

Step-by-step explanation:

This event that's taking place is happening twice. The event is the mail getting delivered. It's happening two times. Luckily, you already know the probability of it happening once. Because it happens twice, you just square it. (0.9)^2. 0.81 chance of it happening in two consecutive days.

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You make the exponent the amount of timeframe. for example since it is two consecutive days, it will be (0.90)^2.  which is 0.81.