Home / 15-20

Finding the Third Proportional to 15 and 20

Calculator

Solution

The third proportional to 15 and 20 is: 26.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    15 : 20 = 20 : x
  2. Step 2: Convert to fraction form
    15/20 = 20/x
  3. Step 3: Cross multiply
    15x = 20 × 20
  4. Step 4: Simplify right side
    15x = 400
  5. Step 5: Solve for x
    x = 400/15
  6. Step 6: Final answer
    x = 26.67

Related Problems

Find third proportional to 7.50 and 10
Half scale
Find third proportional to 30 and 40
Double scale
Find third proportional to 17 and 23
Similar ratio
Find third proportional to 22.50 and 30
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.33) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.