Question

Every second, an elevator either has a 50% chance of going up and a 50% chance of going down. If the elevator starts at floor 15, what is the probability that, after 5 seconds, the elevator is at floor 18?

Answer 1

Using it's concept, it is found that there is a 0.1563 = 15.63% probability that, after 5 seconds, the elevator is at floor 18.

What is a probability?

A probability is given by the number of desired outcomes divided by the number of total outcomes.

Starting at floor 15, these are the following outcomes that result in the elevator being at floor 18 in 5 seconds, each with $0.5^5$ probability:

• 4 up, 1 down.

• 3 up, 1 down, 1 up.

• 1 down, 4 up.

• 1 up, 1 down, 3 up.

• 2 up, 1 down, 2 up.

5 outcomes, hence the probability is:

$p = 5 \times (0.5)^5 = 0.1563$

0.1563 = 15.63% probability that, after 5 seconds, the elevator is at floor 18.

More can be learned about probabilities at https://brainly.com/question/14398287