Answer:
The speed of current is 5 mile per hour
Step-by-step explanation:
Given as :
The speed of boat = x = 20 mph
The distance cover is 75 mile in upstream
Boat goes upstream and back in 8 hours
Let the speed of current = x mph
Now ,
[tex]\frac{75}{20 - x}+\frac{75}{20+x}= 8[/tex]
Or, [tex]\frac{1}{20 - x}+\frac{1}{20+x}= \frac{8}{75}[/tex]
Or, [tex]\frac{(20+x)+(20-x)}{400-x^{2}}=\frac{8}{75}[/tex]
Or,[tex]\frac{40}{400-x^{2}}=\frac{8}{75}[/tex]
Or, 400 - x² = 375
Or, x² = 400 - 375 = 25
∴ x = √25 = 5 mph
I.e speed of current is 5 mph
Hence The speed of current is 5 mile per hour Answer
