Barbie and Woody go from school to a swimming pool, starting at the same time. Barbie walks at 70 meters per minute and Woody cycles 3 times as fast as Barbie walks. 9 minutes later, Woody arrives. How many minutes earlier than Barbie does Woody arrive?

1 Answer
Apr 18, 2018

Woody arrived #27-9 = 18# minutes before Barbie did.

Explanation:

When you are working with Distance=speed-time problems remember that if you know two of the values you can calculate the third one,

Barbie: She walks at a speed of #70# metres per minute.

Woody: Cycles #3# times as fast:#" "rarr 3 xx 70 = 210# m/min
He cycled for #9 # minutes.

#210# m/min is his speed.
#9# minutes is the time he took.

#"Distance" = "speed" xx "time"#

#D= 210 xx9 = 1890# metres,

Barbie: walked the same distance of #1890# metres
Her speed was #70# m/min

The time she took: #"Time" = "distance"/"speed"#

#"Time = 1890/70 = 27 # minutes.

Woody arrived #27-9 = 18# minutes before Barbie did.