Respuesta :
The correct answers are:
A) 60 miles; and B) 3.375 hours.
Explanation:
We will use the equation d = rt for this.
For the first leg of the trip, the bird travels 20 miles per hour for x hours. This gives us the equation
d = 20x
For the return trip, the bird travels 4 miles per hour slower, so 20-4 = 16 miles per hour. He also travels 6 miles less than the return distance, for x hours:
d-6 = 16x
To isolate d, we will add 6 to each side:
d-6+6 = 16x+6
d = 16x+6
We will set the two equations equal to one another, since they both equal d:
20x = 16x+6
Subtract 16x from each side:
20x-16x = 16x+6-16x
4x = 6
Divide both sides by 4:
4x/4 = 6/4
x = 1.5
He travels for 1.5 hours both times.
The first time, 1.5 hours at 20 miles per hour is:
d = 1.5(20) = 30 miles
The original trip is 30 miles. This makes the entire trip 30(2) = 60 miles.
On the return trip, he travels 30-6 = 24 miles at 16 miles per hour:
24 = 16x
Divide both sides by 16:
24/16 = 16x/16
1.5 = x
If he goes 24 miles in 1.5 hours at 16 miles per hour, we can use a proportion to find the time it takes for the entire return trip:
24/1.5 = 30/x
Cross multiplying,
24*x = 1.5(30)
24x = 45
24x/24 = 45/24
x = 1.875
This gives him a total time of 1.5+1.875 = 3.375 hours.
(a) The total distance of the trip is 60 miles
(b) The total time of the motion for the entire trip is 3.375 hours
The given parameters include;
- the speed of the bird in the forward trip = 20 m/h
- time of motion = x
- the speed of the bird in the backward trip in x hours = (20 - 4)m/h = 16 mi/h
- distance remaining to complete the backward trip = 6 miles
The time to complete each trip is calculated as;
[tex]distance = \ speed \times time[/tex]
[tex]forward \ distance = backward \ distance\\\\20x = 16x + 6\\\\20x-16x = 6\\\\4x = 6\\\\x = \frac{6}{4} \\\\x = 1.5 \ hr[/tex]
The total time of the motion for the entire trip is calculated as follows;
Time = time for forward + time for backward
[tex]time = 1.5 \ hr_{forward} \ \ +\ \ 1.5 \ hr_{\ backward } \ + \ \ \frac{6 \ mi}{16 \ mi/hr} _{\ backward}\\\\time = 2(1.5)hr + 0.375\ hr\\\\time = 3.375 \ hr[/tex]
The time for the entire trip is 3.375 hours
The total distance of the trip is calculated as follows;
[tex]total \ distance = forward \ distance + backward \ distance\\\\total \ distance = 20\times 1.5 \ \ + \ 16\times 1.5 \ \ + \ 6 \ miles\\\\total \ distance = 60 \ miles[/tex]
Thus, the total distance of the trip is 60 miles
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