Answer:
10 min.
Step-by-step explanation:
Remember d = rt
The distance from bear's house to beehive = 75m and 225m = distance from beehive to piglet's house
Let r = normal rate of speed
The normal time is 300/r without stopping
75/r = time from bear's house to beehive
225/(r + 15) = time from beehive to piglet's house
So, time from beehive to piglet's house + time at beehive + time from bear's house to beehive = normal time without stopping
225/(r + 15) + 2.5 + 75/r = 300/r
225r + 2.5r(r + 15) + 75(r + 15) = 300(r + 15)
225r + 2.5r^2 + 37.5r + 75r + 1125 = 300r + 4500 Let's remove the deceimal by multiplying thru by 10
2250r + 25r^2 + 375r + 750r + 11250 = 3000r + 45000
25r^2 + 3375r + 11250 = 3000r + 45000
25r^2 + 375r - 33750 = 0
25(r^2 + 15r - 1350) = 0
25(r - 30 )(r + 45) = 0
r = 30 or -45 But, the rate cannot be negative, therefore r = 30
The journey takes 300/30 = 10 min.
