SOLUTION: how do I work out Wally's stride length is 80cm how many strides will he take to cover 16km..I shudder at these, please help

Question 574575: how do I work out Wally's stride length is 80cm how many strides will he take to cover 16km..I shudder at these, please help
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
The way to approach these is to think in terms
of the units only. Work it out as units, and then
plug in the numbers.
Working step-by-step:
( strides / cm ) x ( cm/m )
Rewrite this as:
( cm/cm ) x ( strides/m )
Now you want:
( cm/cm ) x ( strides/m ) x ( m/km )
Now rewrite this as:
( cm/cm ) x ( m/m ) x ( strides/ km )
This is the right approach as far as units go
Everything cancels except ( strides / km )
----------------------------------
Now work backwards toward actual unit conversions:
( strides/cm ) x ( cm/m ) x ( m/km ) = ( strides/km )
This is exactly the same as:
( cm/cm ) x ( m/m ) x ( strides/ km )
with multipliers and divisors just shifted around
Now, and only now, plug in numbers.
multiply by km, and you end up with
a single unit: ( strides ), which is what you want
( strides/cm ) x ( cm/m ) x ( m/km ) x ( km ) = ( strides )

Wally needs 20,000 strides to cover 16 km
----------------
I never, but never, jump right into the numbers. I learned the
units method in high school physics where the teacher would
fill a blackboard with just unit conversions.
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