Question

Alexis took an elevator one floor down from the lobby of her office building to the parking garage. Then she took the elevator back up 5 floors to her office. She described her movement with this expression: 1+5 What was Alexis’ error? She should have used –1 for moving below the lobby. She should have used –5 for moving up 5 floors. She should have used –1 for her movement down and –5 for her movement up. She should have started at zero and then added 6.

Answer 1

A

Explanation:

Answer 2

Her mistake was that she should have used –1 for moving below the lobby.

Explanation:

Lets denote the lobby as Floor zero (0)

- if you go up, you add a positive value to this quantity.

- if you go down, you add a negative value to this quantity.

Lets assume that moving through each floor is equivalent to advancing one unit

* She first took an elevator one floor down

(-1)

Then she took the elevator back up 5 floors to her office

(+5)

Her movement is described by the expression

(-1) + (5)

Her mistake was that she should have used –1 for moving below the lobby.