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Finding the Fourth Proportional to 687.20, 948.42 and 392.50

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Solution

The fourth proportional to 687.20, 948.42 and 392.50 is: 541.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.20 : 948.42 = 392.50 : x
  2. Step 2: Convert to fraction form
    687.20/948.42 = 392.50/x
  3. Step 3: Cross multiply
    687.20x = 948.42 × 392.50
  4. Step 4: Simplify right side
    687.20x = 372,254.85
  5. Step 5: Solve for x
    x = 372,254.85/687.20
  6. Step 6: Final answer
    x = 541.70

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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.