an elevator descends at the rate of 8m/min.if the descent starts from 5m above the ground level,how much time will it take to reach -475m ?

If the original question has a unit of 8m/min., I prefer to give the answer in minutes. The question did not say to answer in hours, and did not say you have to round to the nearest hour.

But it is up to you.

mathmate,she is right,she is trying to say that the answer , if we round up we get 1 hour.

cuz may be her mathbook's back answer is 1 hour or 60 minutes

To determine the time it takes for the elevator to reach -475m, we need to calculate the total distance it needs to travel and divide it by the rate at which it descends.

Given:
Rate of descent: 8 m/min
Starting position: 5 m above the ground level
Target position: -475 m

First, let's find the total distance the elevator needs to travel. The starting position is 5m above ground level, so the initial distance is 5m. The elevator will descend to a position below the ground level, so we need to subtract the target position from the starting position:

Total distance = target position - starting position
= -475 m - 5 m
= -480 m

Now we can divide the total distance by the rate of descent to find the time it takes:

Time = Total distance / Rate of descent
= -480 m ÷ 8 m/min
= -60 min

The negative sign indicates that the elevator is moving downward. Since time cannot be negative, we take the absolute value of -60 min, which gives us 60 min.

Therefore, it will take the elevator 60 minutes to descend to a position of -475m.

Distance travelled

=8-(-475)
=483 m

Speed
= 8 m / min.

Time = Distance ÷ speed
=483÷8
=60.375 minutes

if we round up we get 60min/1 hour