Home / 21-27

Finding the Third Proportional to 21 and 27

Calculator

Solution

The third proportional to 21 and 27 is: 34.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    21 : 27 = 27 : x
  2. Step 2: Convert to fraction form
    21/27 = 27/x
  3. Step 3: Cross multiply
    21x = 27 × 27
  4. Step 4: Simplify right side
    21x = 729
  5. Step 5: Solve for x
    x = 729/21
  6. Step 6: Final answer
    x = 34.71

Related Problems

Find third proportional to 10.50 and 13.50
Half scale
Find third proportional to 42 and 54
Double scale
Find third proportional to 23 and 30
Similar ratio
Find third proportional to 31.50 and 40.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.29) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.