Ellen is at a hydroplane boat show. Starting from 1.0 miles away, the boat drives toward her and then passes her. The boat travels at a constant rate of 70 miles per hour. The distance of the boat from Ellen is given by d=|1.0-70t| at what time is the boat 0.2 miles from Ellen? (Calculate your answer in seconds)
A. 0.7 s and 1.0 s
B. 60 and 70 s
C. 411 s and 617 s
D. 41.1 s and 61.7 s

Question

Ellen is at a hydroplane boat show. Starting from 1.0 miles away, the boat drives toward her and then passes her. The boat travels at a constant rate of 70 miles per hour. The distance of the boat from Ellen is given by d=|1.0-70t| at what time is the boat 0.2 miles from Ellen? (Calculate your answer in seconds)
A. 0.7 s and 1.0 s
B. 60 and 70 s
C. 411 s and 617 s
D. 41.1 s and 61.7 s

anonymous · Answer

Solve$$1-70t=\frac{2}{10}$$for x:$$x=\frac{2}{175}\text{hours}=\frac{2}{175}3600 \sec =41.1429 \sec  $$

anonymous · Answer

So D? @robtobey

anonymous · Answer

Yes, that is what I got.

anonymous · Answer

@

Very Sorry, "for x:" should have been written, "for t:"

anonymous · Answer

No problem! I understood what you meant haha