Ramona cycles from her house to school at 15 miles per hour. Upon arriving, she immediately cycles home at 25 miles per hour. If the entire round-trip takes her 32 minutes, then what is the average speed, in miles per hour for the entire trip?
-
We know that the distance from the school to the house is the same as the distance from the house to the school which gives us the equation:
x*15=y*25
where x and y are the time for the trips in either direction.
And the total time is 32 minutes so we also have:
x+y=32
Isolating x in the first equation gives us x=25/15y=5/3y and inserting this in the second equation gives us: 32=x+y=(5/3)y+y=(8/3)y so y=32*3/8=12. No we can insert again in the second equation to get x=32-12=20. Now we can calculate the average speed:
v=(15*20+25*12)/32=18.75 m/h
x*15=y*25
where x and y are the time for the trips in either direction.
And the total time is 32 minutes so we also have:
x+y=32
Isolating x in the first equation gives us x=25/15y=5/3y and inserting this in the second equation gives us: 32=x+y=(5/3)y+y=(8/3)y so y=32*3/8=12. No we can insert again in the second equation to get x=32-12=20. Now we can calculate the average speed:
v=(15*20+25*12)/32=18.75 m/h
-
va = ( v + v0 ) / 2
va = average velocity
v0 = initial velocity
v = final velocity
va = 24306000 ft/s
v = 47820000 ft/s
v0 = 792000 ft/s
1 foot/seconds = 5.26094276 × 10^-8 miles/hour=0.00000001x5.26094276=n
va = average velocity
v0 = initial velocity
v = final velocity
va = 24306000 ft/s
v = 47820000 ft/s
v0 = 792000 ft/s
1 foot/seconds = 5.26094276 × 10^-8 miles/hour=0.00000001x5.26094276=n
-
assuming the distance from home to school is D
going to school took her D/15 and back home took her D/25 hours
average speed is 2D/(D/15+D/25) = 2/(1/15+1/25) = 150/ (3+5) = 18.75 mph
going to school took her D/15 and back home took her D/25 hours
average speed is 2D/(D/15+D/25) = 2/(1/15+1/25) = 150/ (3+5) = 18.75 mph
-
Let the distance be x miles
x / 15 + x /25 = 32/60 = 8/15
MULTIPLY BY 75
5x + 3x = 40
8x = 40
x = 5 miles
Average speed = distance / time = 10 / 32/60 = 600 /32 = 150 /8 = 18.75 mph ANSWER
CHECK
18.75 X 32/60 = 10miles
x / 15 + x /25 = 32/60 = 8/15
MULTIPLY BY 75
5x + 3x = 40
8x = 40
x = 5 miles
Average speed = distance / time = 10 / 32/60 = 600 /32 = 150 /8 = 18.75 mph ANSWER
CHECK
18.75 X 32/60 = 10miles