Answer:
Annette should plan to spend 2.25 hours walking back.
Explanation:
To solve this problem, we can use the formula:
Time = Distance / Speed
Let's assume the distance of the race is D miles.
Annette spends her time running the distance of the race, which takes:
Time running = D / 9 hours
She then walks back the same distance, which we need to find the time for:
Time walking = D / 3 hours
Since Annette has a total of 3 hours for her training, the sum of the running time and walking time should equal 3 hours:
D / 9 + D / 3 = 3
To simplify the equation, we can multiply all terms by 9 to eliminate the denominators:
D + 3D = 27
Combining like terms:
4D = 27
Dividing both sides of the equation by 4:
D = 6.75
So, the distance of the race is 6.75 miles.
To find the time Annette should spend walking back, we substitute the distance into the time-walking formula:
Time walking = D / 3 = 6.75 / 3 = 2.25 hours
Therefore, Annette should plan to spend 2.25 hours walking back.