SOLUTION: Susan has to finish a journey of 8 km in 1 hour. for the first half of the journey, she walks at 6 km/h. what should be her speed for the second half of the journey?

Question 945122: Susan has to finish a journey of 8 km in 1 hour. for the first half of the journey, she walks at 6 km/h. what should be her speed for the second half of the journey?
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
Half of the journey is 4 km. At a rate of 6 km/hr, it takes (4 km)/(6 km/hr)=2/3 hr to walk the first half. Since she must finish in 1 hour, she has 20 minutes (1/3 hr) remaining to walk the second 4 km so 4km/(1/3 hr)=12 km/hr
ANSWER Susan must walk the second half at 12 km/hr to average 8 km/hr

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