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Finding the Fourth Proportional to 621.08, 856.89 and 399.63

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Solution

The fourth proportional to 621.08, 856.89 and 399.63 is: 551.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.08 : 856.89 = 399.63 : x
  2. Step 2: Convert to fraction form
    621.08/856.89 = 399.63/x
  3. Step 3: Cross multiply
    621.08x = 856.89 × 399.63
  4. Step 4: Simplify right side
    621.08x = 342,438.95
  5. Step 5: Solve for x
    x = 342,438.95/621.08
  6. Step 6: Final answer
    x = 551.36

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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.