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Finding the Fourth Proportional to 47.21, 65.15 and 28.79

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Solution

The fourth proportional to 47.21, 65.15 and 28.79 is: 39.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.21 : 65.15 = 28.79 : x
  2. Step 2: Convert to fraction form
    47.21/65.15 = 28.79/x
  3. Step 3: Cross multiply
    47.21x = 65.15 × 28.79
  4. Step 4: Simplify right side
    47.21x = 1,875.20
  5. Step 5: Solve for x
    x = 1,875.20/47.21
  6. Step 6: Final answer
    x = 39.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.