Question

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?

Answer 1

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: →3 × 70 = 210 m/min

He cycled for 9 minutes.

210 m/min is his speed.

9 minutes is the time he took.

Distance = speed × time

D = 210 × 9 = 1890 metres,

Barbie: walked the same distance of 1890 metres

Her speed was 70 m/min

The time she took:

Time=
`(Distance)/(Speed)`

T i m e =
`(1890)/(70)` = 27 minutes.

Woody arrived 27 − 9 = 18 minutes before Barbie did.