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Finding the Fourth Proportional to 64.20, 96.31 and 20.87

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Solution

The fourth proportional to 64.20, 96.31 and 20.87 is: 31.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.20 : 96.31 = 20.87 : x
  2. Step 2: Convert to fraction form
    64.20/96.31 = 20.87/x
  3. Step 3: Cross multiply
    64.20x = 96.31 × 20.87
  4. Step 4: Simplify right side
    64.20x = 2,009.99
  5. Step 5: Solve for x
    x = 2,009.99/64.20
  6. Step 6: Final answer
    x = 31.31

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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.