## luisz 3 years ago In the morning, Alan drove 100 miles at the rate of 60 miles per hour; in the afternoon, he drove another 100 miles at the rate of 40 miles per hour. What was his average rate of speed, in miles per hour, for the day?

1. luisz

k...

2. luisz

d=100

3. luisz

anything?

4. luisz

ahh

5. luisz

60+40/2=50

6. luisz

derp

7. luisz

C.

8. luisz

no

9. luisz

B.

10. luisz

48

11. luisz

nope

12. luisz

that'swrong

13. luisz

it's 48

14. satellite73

heck no

15. satellite73

oh i mean heck no to 50

16. satellite73

average speed is not the average of the speeds

17. luisz

oh man, you are a guru

18. luisz

you are even higher than DA PANIC!!!!!!

19. Calcmathlete

Oh, sorry...just been a while since I've done these...

20. satellite73

figure out how long it took to get there, then figure out how long it took to get back that is the total time divide the total distance (200 miles ) by the total time to get the average speed

21. luisz

2.5+1.666666667

22. luisz

divided by 200

23. luisz

equal 48

24. luisz

that it?

25. luisz

200/4.166666667?

26. luisz

=48

27. luisz

100/60=5/3

28. luisz

100/40=2.5

29. satellite73

time going it $$\frac{100}{60}$$ time returning is $$\frac{100}{40}$$ total time is $\frac{100}{60}+\frac{100}{40}=\frac{25}{6}$ and $200\div \frac{25}{6}=200\times \frac{6}{25}=8\times 6=48$ as luisz said

30. luisz

5/2+5/3=15/6+10/6=25/6

31. luisz

200 divided by 25/6=48

32. luisz

ty

33. luisz

you nothing about truth tables, guru?

34. satellite73

now redo the problem replacing 100 by $$m$$ and see that the answer is still 48 mph

35. luisz

by friend, aripotta needs help with them?

36. satellite73

yes, we can do them

37. satellite73

38. luisz

its not me who needs help with them

39. luisz

its aripotta

40. luisz

I'm posting a different problem