Averages, the Missing Score, and Simple Probability
Add and divide for the average, use the total to find a missing score, then use median, mode and simple probability as quick counting methods.
What it is
This lesson is about describing a set of numbers with one number, and about measuring chance.
- The average (also called the mean) is the value every item would have if the total were shared out equally.
- The missing score problem gives you the average and all values but one. You find the one that is missing.
- The median is the middle value after sorting, and the mode is the value that appears most often.
- Simple probability tells how likely an event is, as a fraction from 0 (impossible) to 1 (certain).
Why it matters on the exam
Average items appear in almost every Numerical Ability set: grades, daily sales, monthly bills, attendance. The missing-score type ("What must she get on the last test?") is one of the most common word problems. The newest practice tests also include a few items on median, mode and probability.
At work you use the same skills to report average monthly expenses, typical processing time, or the chance that a randomly picked file has an error.
- ₱4,160
- ₱4,992
- ₱4,135
- ₱4,250
The rest of this lesson, and every other lesson, is part of ReviewTayo.
Read moreIn the full lesson
- How to recognize it on the test
- What to look for (5 checks)
- All 4 rules and tools
- 4 worked examples, every step explained
- 6 common mistakes and how to fix them
- 3 exam techniques
- Remember: 5 key points
- Practice questions with explanations, and your progress saved
More Numerical Ability lessons
ReviewTayo has 47 lessons that follow the official scope of the exam, each with rules, worked examples, common mistakes and practice. Open one and read the first part.