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Finding the Fourth Proportional to 92.40, 138.78 and 76.20

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Solution

The fourth proportional to 92.40, 138.78 and 76.20 is: 114.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.40 : 138.78 = 76.20 : x
  2. Step 2: Convert to fraction form
    92.40/138.78 = 76.20/x
  3. Step 3: Cross multiply
    92.40x = 138.78 × 76.20
  4. Step 4: Simplify right side
    92.40x = 10,575.04
  5. Step 5: Solve for x
    x = 10,575.04/92.40
  6. Step 6: Final answer
    x = 114.45

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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.