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Finding the Fourth Proportional to 687.60, 948.78 and 392.85

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Solution

The fourth proportional to 687.60, 948.78 and 392.85 is: 542.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.60 : 948.78 = 392.85 : x
  2. Step 2: Convert to fraction form
    687.60/948.78 = 392.85/x
  3. Step 3: Cross multiply
    687.60x = 948.78 × 392.85
  4. Step 4: Simplify right side
    687.60x = 372,728.22
  5. Step 5: Solve for x
    x = 372,728.22/687.60
  6. Step 6: Final answer
    x = 542.07

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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.