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# help with rates

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Linda drove 50 miles from San Jose to San Francisco in 90 minutes. For the first 30minutes, without much traffic, her average speed was 60 miles an hour. In the second 30 minutes, due to a traffic accident along US 101, her average speed dropped to 25 miles an hour. She was stuck in traffic for the last 30 minutes near San Francisco.What was her average speed, in miles per hour, during the last 30 minutes?

Jul 1, 2021

#1
+33376
+2

Total distance  50 miles

30 minutes @ 60 m/ hr = 30 miles       20 miles to go

30 minutes @ 25 m/hr  = 12.5 miles    7.5 miles to go

last 30 minutes she went 7.5 miles       30 minutes = 1/2 hr     7.5 miles / (1/2 hour) = 15 m/hr during last 30 minutes

Jul 1, 2021

#1
+33376
+2

Total distance  50 miles

30 minutes @ 60 m/ hr = 30 miles       20 miles to go

30 minutes @ 25 m/hr  = 12.5 miles    7.5 miles to go

last 30 minutes she went 7.5 miles       30 minutes = 1/2 hr     7.5 miles / (1/2 hour) = 15 m/hr during last 30 minutes

ElectricPavlov Jul 1, 2021