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Finding the Fourth Proportional to 620.28, 856.68 and 399.36

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Solution

The fourth proportional to 620.28, 856.68 and 399.36 is: 551.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.28 : 856.68 = 399.36 : x
  2. Step 2: Convert to fraction form
    620.28/856.68 = 399.36/x
  3. Step 3: Cross multiply
    620.28x = 856.68 × 399.36
  4. Step 4: Simplify right side
    620.28x = 342,123.72
  5. Step 5: Solve for x
    x = 342,123.72/620.28
  6. Step 6: Final answer
    x = 551.56

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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.