Steve goes on the elevator at the 11th floor of a bldg. and rides up at a rate of 57 floors per minute. At the same time Joyce gest on an elevator on the 51st fllor of the same bldg. and rides down at a rate of 63 floor per minute. If they continue traveling at ethese rates, at which floor will they meet?
I need to see the steps...thanks!
Problem from Kaplan Diag. Test
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Last edited by isisalaska on Thu Mar 22, 2007 2:51 pm, edited 1 time in total.
Isis Alaska
- Neo2000
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The difference in floors is 40
Both of them will travel for the same time t
However distance(floors) travelled will be different say X
Time = Distance/Speed
If Time is Constant
D1/S1 = D2/S2
X/(47/60) = (40-X)/(63/60)
Can you simplify from here?
Both of them will travel for the same time t
However distance(floors) travelled will be different say X
Time = Distance/Speed
If Time is Constant
D1/S1 = D2/S2
X/(47/60) = (40-X)/(63/60)
Can you simplify from here?
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- jayhawk2001
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Just posting a slightly elaborate version
1 sec rates for each elevator = 57 / 60 and 63 / 60 floors resp.
11 + x * 57/60 = 51 - x * 63/60
x * 120 / 60 = 40
x = 20 sec
So, floor that they will meet = 11 + 20 * 57/60 = floor num 30
1 sec rates for each elevator = 57 / 60 and 63 / 60 floors resp.
11 + x * 57/60 = 51 - x * 63/60
x * 120 / 60 = 40
x = 20 sec
So, floor that they will meet = 11 + 20 * 57/60 = floor num 30
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I don't know about the elaborate explanations but I tried a very basic trial and error method...here it goes
First Elevator - 57 floors / minute
= 57 floors / 60 seconds
Therefore in one second 57 / 60 = 19 / 20 floors
Second Elevator - 63 floors / minute
= 63 floors / 60 seconds
Therefore in one second 63 / 60 = 21 / 20 floors
After 20 seconds Elevator 1 = 19/20 * 20 = 19 floors up = 11th floor + 19 floors = 30th floor
After 20 seconds Elevator 2 = 21/20 * 20 = 21 floors down = 51-21 = 30th floor
Hence they meet at the 30th floor
First Elevator - 57 floors / minute
= 57 floors / 60 seconds
Therefore in one second 57 / 60 = 19 / 20 floors
Second Elevator - 63 floors / minute
= 63 floors / 60 seconds
Therefore in one second 63 / 60 = 21 / 20 floors
After 20 seconds Elevator 1 = 19/20 * 20 = 19 floors up = 11th floor + 19 floors = 30th floor
After 20 seconds Elevator 2 = 21/20 * 20 = 21 floors down = 51-21 = 30th floor
Hence they meet at the 30th floor