A patient weighs 14 kg and requires drug A at a dose of 5 mg/kg per day. What is the total daily dose for this patient?

2 Answers
256
Jan 22, 2017

#70 mg#

Explanation:

First off is the cancellation of dimensions

#14 kg * 5 (mg)/(kg)=14cancel(kg)*5(mg)/(cancel(kg))=(14*5)mg#

For simplicity you can split 14 up and distribute

#=((10+4)*5)mg=((5(10)+5(4))mg=(50+20)mg#

#=70mg#

Tony B
Jan 22, 2017

#70 mg#

Explanation:

Use the units of measurement to guide as to how to do the calculation.

You need to end up with just #mg#

We are given #color(red)(Kg) and color(green)( (mg)/(Kg))#

If we do this: #color(red)(Kg)color(green)(xx(mg)/(Kg)# we end up with:

#color(green)((color(red)(Kg))/(Kg)xxmg ->(cancel(color(red)(Kg)))/cancel((Kg))xxmg" " # as required

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Doing the same thing with the numbers:

#14 color(white)(.)color(red)(Kg)xx5 color(white)(.) color(green)((mg)/(Kg)) = 70 mg#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A quick way of calculating #14xx5# is to think of 5 as #10/2#

#10xx14=140 and 1/2xx140=70#

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