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Finding the Fourth Proportional to 312.54, 468.78 and 81.42

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Solution

The fourth proportional to 312.54, 468.78 and 81.42 is: 122.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.54 : 468.78 = 81.42 : x
  2. Step 2: Convert to fraction form
    312.54/468.78 = 81.42/x
  3. Step 3: Cross multiply
    312.54x = 468.78 × 81.42
  4. Step 4: Simplify right side
    312.54x = 38,168.07
  5. Step 5: Solve for x
    x = 38,168.07/312.54
  6. Step 6: Final answer
    x = 122.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.