It will take fran 0.67 hours to swim 1.8 mi upstream
it will take fran 0.25 hours to swim 1.8 mi downstream
Step-by-step explanation:
Fran's speed in still water= 5mph
speed of the river=2.3 mph
upstream journey
speed while swimming upstream= speed in still water-speed of the river=5-2.3=2.7mph
distance to be traveled upstream=1.8 miles
Time taken to swim= upstream distance/upstream speed
=1.8/2.7
=0.67 hours
Fran will take 0.67 hours to swim upstream
downstream journey
speed while swimming downstream= speed of Fran+speed of the river
=5+2.3=7.3mph
distance to be travelled downstream=1.8 miles
time taken=downstream distance/ downstream speed
=1.8/7.3=0.25 hours