Question

Emily rows six miles downstream in 1 hour and her friend Ashley, rowing 1 mile per hour faster, completes the return trip in 2 hours.

If Emily and Ash ley were rowing separately, who would complete their trip first and by how long? Round to the nearest hundredth, if necessary.

speed of the current:2mph.

rowing speed of Emily.

rowing speed of Ashley.

Answer 1

emily rows downstream (with the current); she takes 1 hour to go 6 miles. The current is 2mph and Emily's total speed is 6mph (she covers 6 miles in 1 hour so 6mph) so Emily rows at 4mph.

Ashley rows 1 mph faster s0 Ashley's rowing speed is 5mph.

(Check -- rowing at 5mph against a current of 2mph means she travels at 3mph. Going 6 miles at 3mph requires 2 hours, which is the time given.)

Suppose that Emily and Ashley separately rowed the entire 12 mile trip -- 6 miles downstream and 6 miles back upstream.

Emily rows at 4mph. Thus her downstream speed is 6mph (with the current) and her upstream speed is 2mph (against the current). Use so the time required is the distance divided by the rate. So Emily's time for the course is the sum of the downstream and upstream legs. so Emily's course time is 4 hours.

Ashley rows at 5mph. Her downstream speed is 7mph and her upstream speed is 3mph. The time is

hours.

Ashley's course time is 2.86 hours.

Ashley will complete her trip first by approximately 1.14 hours. (1 hour and 8.4 minutes)