Unit 1 : A Ribbon Problem – Bar Model Approach

The write-up shows a latest update with an variant of a recent PSLE question(10/2/2017) illustrating the use of the model of Euclidean Division Algorithm

Jane, a sales supervisor, prepared 150 pieces of ribbons of length 160 cm for gift wrapping. The ribbons are to be cut from rolls of length 20 m each.
What is the least number of rolls needed?

For each roll of length 20 m = 2000 cm, the bar model shows that Jane can have 12 ribbons  with the remaining 80 cm of ribbon to be discarded.

For 150 pieces pf ribbons, the bar model shows that one roll is needed for 12 ribbons.

Number of rolls needed is 12 + 1 = 13.

The problem illustrates the use of bar models to give a  pictorial view of the correct situations.