Respuesta :
Answer:
Cycling rate = 12 mph
Explanation:
After riding a bicycle at a steady speed for 40 miles, John had a flat tire and walked 5 miles to a repair shop.
Total distance covered = 40 + 5 = 45 miles
His cycling rate was 4 times faster than his walking rate.
Let the walking rate be w.
Cycling rate = 4w
If the time spent cycling and walking was 5 hours
That is
[tex]\frac{40}{4w}+\frac{5}{w}=5\\\\40w+20w=20w^2\\\\20w^2=60w\\\\w=3mph[/tex]
Cycling rate = 4w = 4 x 3 = 12 mph
Cycling rate = 12 mph
Using the speed - time relation, the riding rate of the cyclist ls 12 miles per hour.
Let :
- walking speed = s
- Cycling speed = 4s
- Total distance = 40 + 5 = 45 miles
- Total time spent = 5 hours
Recall :
- Time taken = Distance / speed
- Walking time = 5/s
- Cycling time = 40/4s
Total time taken = cycling time + walking time
5 = 5/s + 40/4s
5 = (20 + 40) / 4s
Cross multiply
4s × 5 = 60
20s = 60
s = 60/20
s = 3
Therefore, cycling speed = 4(3) = 12 miles per hour.
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