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Finding the Fourth Proportional to 621.28, 856.96 and 399.88

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Solution

The fourth proportional to 621.28, 856.96 and 399.88 is: 551.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.28 : 856.96 = 399.88 : x
  2. Step 2: Convert to fraction form
    621.28/856.96 = 399.88/x
  3. Step 3: Cross multiply
    621.28x = 856.96 × 399.88
  4. Step 4: Simplify right side
    621.28x = 342,681.16
  5. Step 5: Solve for x
    x = 342,681.16/621.28
  6. Step 6: Final answer
    x = 551.57

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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.