Answer:
Explanation:
Distance = Speed * time
If a bird leaves it's nest and travels 15 miles per hour downwind for x hours, the distance covered will be:
D = 15x
x = D/15 ....... 1
If on the return trip, the bird travels 3 miles per hour slower and has 2 miles left after x hours
Her speed = 15 - 3 = 12mi/hour
If she has 2 miles left after x hours, new distance will be D-2, using the formula for distance:
D+2 = 12x
x = D-2/12 ....... 2
Equate 1 and 2:
D/15 = D-2/12
Cross multiply
12D = 15(D-2)
12D = 15D - 30
12D-15D = -30
-3D = -30
D = 10 miles
The distance for the entire trip will be D + (D-2) = 10 + (10-2)
= 10 + 8
= 18 miles
To get the time x, we will substitute D = 10 into equation1
D = 15x
10 = 15x
x = 10/15
To minutes
x = 10/15 * 60
x = 40 minutes
For the going trip
Time taken = x hours
Return trip = x hours
Total time for the entire trip = x+x = 2x
= 2(40)
= 80 minutes
Hence the total time taken for the entire trio will be 1 hour 20minutes