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Finding the Fourth Proportional to 620.84, 856.71 and 399.86

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Solution

The fourth proportional to 620.84, 856.71 and 399.86 is: 551.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.84 : 856.71 = 399.86 : x
  2. Step 2: Convert to fraction form
    620.84/856.71 = 399.86/x
  3. Step 3: Cross multiply
    620.84x = 856.71 × 399.86
  4. Step 4: Simplify right side
    620.84x = 342,564.06
  5. Step 5: Solve for x
    x = 342,564.06/620.84
  6. Step 6: Final answer
    x = 551.78

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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.