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Finding the Fourth Proportional to 98.20, 135.54 and 56.78

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Solution

The fourth proportional to 98.20, 135.54 and 56.78 is: 78.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.20 : 135.54 = 56.78 : x
  2. Step 2: Convert to fraction form
    98.20/135.54 = 56.78/x
  3. Step 3: Cross multiply
    98.20x = 135.54 × 56.78
  4. Step 4: Simplify right side
    98.20x = 7,695.96
  5. Step 5: Solve for x
    x = 7,695.96/98.20
  6. Step 6: Final answer
    x = 78.37

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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.