A man decides to travel 80 kilometers in 8 hours partly, by foot and partly on a bicycle. If his speed on foot is 8 km/hr and on bicycle 16 km/hr. what distance would he travel on foot?
A man decides to travel 80 kilometers in 8 hours partly, by foot and partly on a bicycle. If his speed on foot is 8 km/hr and on bicycle 16 km/hr. what distance would he travel on foot? Correct Answer 48 km
Given:
A man travel 80 km in = 8 hours
His speed on foot = 8 km/hr
His speed on bicycle = 16 km/hr
Formula:
Speed = Distance/Time
Mixture and Allegation method:
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Where, a > c > b
Calculation:
Short Trick:
Average speed of man = 80/8 = 10 km/hr
Using allegation method
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Time ratio of distance cover with the speed of 8 km/hr to that of 16 km/hr = 6 : 2
⇒ Time taken to cover distance by foot = 6/8 × 8 = 6 hr
∴ Distance covered by on foot = 8 × 6 = 48 km
Detailed method:
Let distance covered on foot be x km
⇒ Distance covered by bicycle = (80 – x) km
According to the question
x/8 + (80 – x)/16 = 8
⇒ (2x + 80 – x)/16 = 8
⇒ x + 80 = 128
⇒ x = 128 – 80
⇒ x = 48 km
∴ Distance covered by foot is 48 km.