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Finding the Fourth Proportional to 645.75, 891.20 and 383.72

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Solution

The fourth proportional to 645.75, 891.20 and 383.72 is: 529.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.75 : 891.20 = 383.72 : x
  2. Step 2: Convert to fraction form
    645.75/891.20 = 383.72/x
  3. Step 3: Cross multiply
    645.75x = 891.20 × 383.72
  4. Step 4: Simplify right side
    645.75x = 341,964.89
  5. Step 5: Solve for x
    x = 341,964.89/645.75
  6. Step 6: Final answer
    x = 529.56

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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.