Probability on the Digital SAT: the Desmos Method
Every probability question on this test is one fraction: the number of things that count, over the number of things you are choosing from. Your only real job is picking those two numbers. Desmos does the dividing and the reducing.
Problem Solving & Data Analysis·65 practice problems in DesPrep
The Probability lesson is part of DesPrep
It is one of the 17 full lessons inside the subscription — 7 sections that take probability from first principles to the fastest Desmos route, with a worked example on every one:
- One fraction, two numbers
- Let Desmos reduce it
- Not, and neither: count what fails, then subtract
- Which total does the question restrict you to
- Two draws: did the bag change?
- At least one means subtract the one way it fails
- Running it backwards, from a probability to a count
Then 65 practice problems on this skill alone, solved inside a live Desmos calculator with step feedback and an expert replay on every one.
More Problem Solving & Data Analysis guides
- Scatterplots and ModelsGraph a line of best fit and read predictions straight off it, instead of substituting by hand.
- Ratios, Rates, Proportions and UnitsTurn a rate into a line and read any proportional value off it in seconds.
- PercentagesPercent change and growth, set up so Desmos does the arithmetic and the graph shows the trend.
- Distributions, Center and SpreadMeans, medians and ranges computed in the Desmos list bar rather than on paper.