Question

I need help with Question 14 . I need to submit it by monday... Pls help

Answer 1

Answer:

Distance between A and B is 5400 meters

Step-by-step explanation:

Consider "D" the letter to identify distance between A and B

Let's use "t" to identify the time of the first encounter (Devi and Kumar), and create an equation that states that the distance covered by Devi (at 100 m/min) in time "t", is equal to the total distance D minus what Kumar has covered at his speed (80 m/min) in that same time:

Recall that distance equals the speed  times the time:

distance= speed * time

First encounter:

100 * t = D - 80 * t

180 * t = D    Equation (1)

Not, 6 minutes later (at time t+6) , Devi and Li Ting meet .

Then for this encounter the distance covered by Devi equals total distance d minus the distance covered by Li Ting:

100 *(t+6) = D - 75 * (t+6)

100 t + 600 = D - 75 t - 450

175 T + 150 = D    Equation (2)

Now, let's equal equation (1) to equation (2), since D should be the same:

180 t = 175 t + 150

5 t = 150

t = 30

Then the time t (first encounter) is 30 minutes. Knowing this, we can use either equation to find D:

From Equation (1) for example: D = 180 * t = 180 * 30 = 5400 meters