Sunday, September 25, 2011

P5 percentage ( proportional thinking


Here, there are 2 percentage systems used here.  60% referencing to the rod and 24% referencing to the rope.

I have chosen to convert one of the 1st percentage system to fraction.  This hopefully helps to make clear that they are separate systems.
For the 2nd percentage system, I still make use of the "%" symbol.  And I use the model to clarify the question even further.

60% = 3/5

.      _________?____________
.     /                      \
Rod  |----|----|----|----|----|
Rope |--------------|-------------------------|
.     \_____   ____/
.           24%
.     \________________    __________________/
.                      100%

    1unit --> 24% / 3 = 8%
Rod (5units) --> 5 x 8% = 40%
Rod:Rope = 40% : 100%  = 2:5