Question 100087
She leaves home at 8am trotting at a speed of 7mph. Her little lamb leaves home at at 8:15am running at a speed of 12 mph. What time of day will the lamb catch Mary? Round your answer to the nearest minute.
:
Let t = time from 8am L catches M
Then
(t-(1/4)) = L,s time running. Changed 15 min to hrs: 15/60 = 1/4)
: 
When L catches M, they will have traveled the same distance. 
Make a simple equation from this fact.
:
Dist = speed * time
:
7t = 12(t-(1/4))
:
7t = 12t - 3
:
7t - 12t = -3 
:
-5t = -3
:
t = -3/-5
:
t = +.6 hrs; .6 * 60 = 36 min
:
L catches M at 8:36 am
:
:
Check solution by seeing if the distances are equal
M: 7 * .6 = 4.2 mi
L: 12(.6-.25) = 4.2 mi also