Mark noticed that his bus is late to school 5% of the time. he wants to design a spinner he can use to simulate the situation and determine the probability that the bus will be late three times next week.

how should mark divide his spinner to best simulate the situation?

The more painstaking way would be to divide up the spinner up into 100 pieces, and shade in 5 of those pieces. Since 5/100 = 0.05 = 5% this means that landing on any of the 5 pieces has a 5% chance of happening. A better way to do this is use 20 slices instead. This works because 5/100 reduces to 1/20 (divide the top and bottom by 5 ). Instead of shading in 5 slices, Mark should shade in 1 . Using a calculator, you should see that 1/20 = 0.05 = 5% as well. The second option is more common but even then a spinner with 20 sections is still a lot. It will be much better for Mark to pull some random numbers out of a hat or anything other accessories, or let a computer generate random numbers.