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Finding the Fourth Proportional to 687.55, 948.90 and 392.81

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Solution

The fourth proportional to 687.55, 948.90 and 392.81 is: 542.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.55 : 948.90 = 392.81 : x
  2. Step 2: Convert to fraction form
    687.55/948.90 = 392.81/x
  3. Step 3: Cross multiply
    687.55x = 948.90 × 392.81
  4. Step 4: Simplify right side
    687.55x = 372,737.41
  5. Step 5: Solve for x
    x = 372,737.41/687.55
  6. Step 6: Final answer
    x = 542.12

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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.