Numerical aptitude · Ratios and averages
Problems on ages, made easy
💡 The idea
Everyone gets older by the same number of years. Write the ages now with a letter, then move forward or back.
5 years ago
x − 5→Now
x→In 5 years
x + 5
x − 5→Now
x→In 5 years
x + 5
🧭 The method: 3 steps
- Call the unknown age now x (or use parts for a ratio).
- Write the other times: x + years, x − years.
- Turn the sentence into an equation and solve.
🎬 Every kind of question, in pictures
Pick a kind. Guess the answer first, then watch the picture work it out. Tap any step to see it in the picture.
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✏️ Worked examples
Example 1. Two ages are in the ratio 3 : 5 and add up to 40. The older is?
- Parts = 3 + 5 = 8
- One part = 40 ÷ 8 = 5
- Older = 5 × 5 = 25
Example 2. In 10 years Maya will be twice as old as she was 5 years ago. Her age now?
- Now = x
- x + 10 = 2 × (x − 5)
- x + 10 = 2x − 10
- x = 20
⚠️ Where people go wrong
- Check whether the question asks for the age now or later.
- Ratios usually change over time: don’t keep the old ratio for the future.
📌 Remember
- In n years: + n for everyone
- n years ago: − n for everyone