Answer:
1. r = 80 km/h
2. The current is flowing at 4.25 mph
Step-by-step explanation:
1. Distance = rate * time
Distance = r * 2.5
If he increase the rate by 20 = (r+20),
the time is 30 minute = .5 hours less =(t-.5)
The time was 2.5 hours = (2.5-.5) = 2 hours
Distance = (r+20) 2 hours
The distance is the same so we set the equations equal
2.5r = 2 * (r+20)
Distribute
2.5r = 2r +40
Subtract 2r from each side
2.5r -2r = 2r-2r +40
.5r = 40
Divide by .5
.5r /.5 = 40/.5
r = 80 km/h
2. Distance = rate * time
rate = 60-r time = 15 minutes/60 minute = .25 hours
Distance = (60-r) * .25
where r is the rate of the current
While drifting it is affected by the current only
Now time = 3 hours 45 minutes = 3 .75 hours
Distance is the the distance it traveled while jetskiing plus 2 miles
Distance +2 = r* (3.75)
Substituting for distance
(60-r) * .25 +2 = 3.75 r
Distribute
15 -.25r +2 = 3.75r
Combine like terms
17 -.25r = 3.75r
Add .25r to each side
17-.25r +.25r = 3.75r +.25r
17 = 4r
Divide by 4
17/4 = 4r/4
4.25 =r
The current is flowing at 4.25 mph
Answer:
Step-by-step explanation:
1. let planned speed be x
distance planned=2.5x
new speed=x+20
new time=2.5-30/60 cuz' theres 60min in 1 hr
=2.5-0.5=2
so distance planned=2(x+20)
2(x+20)=2.5x
2x+40=2.5x
0.5x=40
x=80km/h
2. let rate of current be x
ski's total time in water=3h45m+15m=4h
total distance by current drift=4x
ski motor'd upstream at 60mph for 15m i.e. 0.25h
distance motor'd is -ve as it is "upstream"
=-60(0.25)=-15mile
combining motor'd n drift distances, 4x-15=2
4x=17
x=4.25mph
