Home / 21.24-31.80-20.56

Finding the Fourth Proportional to 21.24, 31.80 and 20.56

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Solution

The fourth proportional to 21.24, 31.80 and 20.56 is: 30.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.24 : 31.80 = 20.56 : x
  2. Step 2: Convert to fraction form
    21.24/31.80 = 20.56/x
  3. Step 3: Cross multiply
    21.24x = 31.80 × 20.56
  4. Step 4: Simplify right side
    21.24x = 653.81
  5. Step 5: Solve for x
    x = 653.81/21.24
  6. Step 6: Final answer
    x = 30.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.