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Finding the Fourth Proportional to 687.54, 948.78 and 392.78

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Solution

The fourth proportional to 687.54, 948.78 and 392.78 is: 542.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.54 : 948.78 = 392.78 : x
  2. Step 2: Convert to fraction form
    687.54/948.78 = 392.78/x
  3. Step 3: Cross multiply
    687.54x = 948.78 × 392.78
  4. Step 4: Simplify right side
    687.54x = 372,661.81
  5. Step 5: Solve for x
    x = 372,661.81/687.54
  6. Step 6: Final answer
    x = 542.02

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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.