Ratio Change Two Points
Ratio Change Two Points problems give the ratio of ages at two different points in time (e.g., present and future, or past and present). These require solving for present ages using both ratio conditions.
What You'll Learn
Introduction to Ratio Change Two Points
Ratio Change Two Points problems give the ratio of ages at two different points in time (e.g., present and future, or past and present). These require solving for present ages using both ratio conditions.
Prerequisites
How to Solve Ratio Change Two Points Problems
Step 1: Let present ages be expressed with a variable (e.g., A=ak, B=bk)
Step 2: Express ages at the other time point (add/subtract years)
Step 3: Set up the second ratio equation
Step 4: Cross-multiply and solve for k
Step 5: Calculate both ages at both time points
Step 6: Verify both ratio conditions
Example Problem
Example: The ratio of A's age to B's age is 3:4 now. After 10 years, the ratio becomes 4:5. Find present ages. Solution: Step 1: A = 3k, B = 4k Step 2: After 10 years: (3k+10)/(4k+10) = 4/5 Step 3: 5(3k+10) = 4(4k+10) → 15k+50 = 16k+40 → 50-40 = 16k-15k → 10 = k Step 4: A = 30, B = 40 years Answer: A=30, B=40 years
Pro Tips & Tricks
- If ratios are a:b (present) and c:d (after n years), then k = n(c-d)/(ad-bc)
- If ratios are given for past and present, use subtraction
- The ratio always moves toward 1:1 over time
- Check if k is positive and yields reasonable ages
- The older person's ratio term is usually larger initially
- For two points, one equation is sufficient to find k
Shortcut Methods to Solve Faster
Common Mistakes to Avoid
Practice Worksheets
Practice makes perfect! Work through these worksheets to master Ratio Change Two Points. Each worksheet contains 20 questions with detailed explanations. Start from Worksheet 1 and progress through increasing difficulty levels.
Exam Importance
Ratio Change Two Points is an important topic for various competitive exams. Here's how frequently it appears:
Ready to Master Ratio Change Two Points?
Start with Worksheet 1 and work your way up to expert level! Each worksheet includes: