julie drives 100 mimi to grandmother's house. on the way to grandmother's, julie drives half the distance at 34.0 mphmph and half the distance at 66.0 mphmph . on her return trip, she drives half the time at 34.0 mphmph and half the time at 66.0 mphmph .

Sagot :

The average speed is r=50 mph

What is speed?

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In essence, an object's speed indicates how quickly it is moving. Its velocity reveals how quickly it is moving in a specific direction. In your daily life, you utilize speed measures, but in physics, velocity measurements are more frequently used.

distance=rate*time

total distance=rate*total time

to Grandmother's...

50=34*t

50/34=t

t=25/17 hours for the first 50 miles

50=66*t

50/66=t

t=25/33 hours for the second 50 miles

total distance=50+50=100 miles

total time=25/17+25/33

total time=(825/561)+(425/561)=1250/561 hours

total distance=rate*total time

100=r*(1250/561)

r=(100)(561/1250)

r=56,100/1250

r=5610/125

r=1122/25

r=44.88 mph is the average speed (rounded it is 44.9 mph)

Note: If you are familiar with the simplified form of the harmonic mean you can solve the problem that way. If not, that's okay. You can look it up if you like.

(2*34*66)/(34+66)=4488/100=44.88 again

from Grandmother's house...

because the times are the same you simply add the 2 rates and divide by 2

(34+66)/2=100/2=50 mph is the average speed

d=r*t

100=34*t+66*t (the times are the same, t)

100=100*t

t=1 hour traveling at 34 mph and 1 hour traveling at 66 mph for a total of 2 hours traveling

d=r*t

100=r*2

r=100/2

r=50 mph is the average speed

To learn more about speed, Visit: https://brainly.com/question/13263542

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