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Finding the Fourth Proportional to 621.12, 856.90 and 400.21

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Solution

The fourth proportional to 621.12, 856.90 and 400.21 is: 552.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.12 : 856.90 = 400.21 : x
  2. Step 2: Convert to fraction form
    621.12/856.90 = 400.21/x
  3. Step 3: Cross multiply
    621.12x = 856.90 × 400.21
  4. Step 4: Simplify right side
    621.12x = 342,936.81
  5. Step 5: Solve for x
    x = 342,936.81/621.12
  6. Step 6: Final answer
    x = 552.13

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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.