SOLUTION: a cyclist went 1km up a hill at 15km per hour then she went down the hill at 30km per hour show that her average speed for the 2km was 20km per hour

Question 261795: a cyclist went 1km up a hill at 15km per hour then she went down the hill at 30km per hour show that her average speed for the 2km was 20km per hour
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
D=RT
2=20T
T=2/20
T=.1 HOUR.
1=15*X
1=30(.1-X)
15X=30(.1-X)
15X=3-30X
15X+30X=3
45X=3
X=3/45
X=.0666 ANS FOR THE TIME GOING UP THE MOUNTAIN.
.1-.0666=.0334 ANS. FOR THE MINUTES DOWN THE MOUNTAIN.
PROOF:
15*.0666=30(.1-.0666)
1=30*.0334
1=1

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