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Finding the Fourth Proportional to 620.70, 856.56 and 387.78

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Solution

The fourth proportional to 620.70, 856.56 and 387.78 is: 535.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.70 : 856.56 = 387.78 : x
  2. Step 2: Convert to fraction form
    620.70/856.56 = 387.78/x
  3. Step 3: Cross multiply
    620.70x = 856.56 × 387.78
  4. Step 4: Simplify right side
    620.70x = 332,156.84
  5. Step 5: Solve for x
    x = 332,156.84/620.70
  6. Step 6: Final answer
    x = 535.13

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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.