Once the call button has been pushed it takes 32 minutes on

Once the call button has been pushed, it takes 3.2 minutes on average for an elevator to arrive in the MATH building. Let E be the time an individual waits until the elevator arrives.

- Suppose it takes an individual 4 minutes to reach the first floor of the math building from the 8th floor when they take the stairs. If an individual takes the elevator, it will only take them 30 seconds to reach the first floor from the 8th floor. Mary has been waiting 2 minutes for an elevator already. Should Mary wait or take the stairs if she wants to reach the first floor more quickly?

Solution

mary should wait more for the elevator

because on an average elevator takes 3.2 minutes to come and mary has alread wait 2 minutes

so in around 1.2 minutes lift will come and in 30 seconds more she will be on 1st floor total will be max 2 minutes more

but if she dont wait and go for stairs

it will take her 4 minutes

in any case waiting for lift is good idea to reach early