Jan lives x floors above the ground floor of a highrise building. It takes her 30 seconds per floor to talk down the...

BTGmoderatorLU wrote: ↑

Mon Feb 08, 2021 11:56 am

Source: Official Guide

Jan lives x floors above the ground floor of a highrise building. It takes her 30 seconds per floor to walk down the steps and 2 seconds per floor to ride the elevator. If it takes Jan the same amount of time to walk down the steps to the ground floor as to wait for the elevator for 7 minutes and ride down, then x equals

A. 4
B. 7
C. 14
D. 15
E. 16

The OA is D

Solution:

Since 7 minutes = 420 seconds, we can create the equation:

Jan’s time to walk = Jan’s time to ride

30x = 420 + 2x

28x = 420

x = 15

Answer: D

BTGmoderatorLU wrote: ↑

Mon Feb 08, 2021 11:56 am

Source: Official Guide

Jan lives x floors above the ground floor of a highrise building. It takes her 30 seconds per floor to walk down the steps and 2 seconds per floor to ride the elevator. If it takes Jan the same amount of time to walk down the steps to the ground floor as to wait for the elevator for 7 minutes and ride down, then x equals

A. 4
B. 7
C. 14
D. 15
E. 16

The OA is D

Let's first convert 7 minutes to SECONDS in order to have uniform units of measurement.
7 minutes = 420 seconds

Let's start with a word equation
Jan's travel time (in seconds) WALKING down = Jan's travel time (in seconds) via ELEVATOR + 420 seconds

It takes her 30 seconds per floor to walk down the steps and 2 seconds per floor to ride the elevator.
There are x floors
So, WALKING time (in seconds) = 30x
And ELEVATOR time (in seconds) = 2x

Plug values into word equation to get: 30x = 2x + 420
Subtract 2x from both sides to get: 28x = 420
Solve: x = 420/28
= 60/4
= 15

Answer: D

Cheers,
Brent