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Finding the Fourth Proportional to 98.94, 136.40 and 78.18

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Solution

The fourth proportional to 98.94, 136.40 and 78.18 is: 107.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.94 : 136.40 = 78.18 : x
  2. Step 2: Convert to fraction form
    98.94/136.40 = 78.18/x
  3. Step 3: Cross multiply
    98.94x = 136.40 × 78.18
  4. Step 4: Simplify right side
    98.94x = 10,663.75
  5. Step 5: Solve for x
    x = 10,663.75/98.94
  6. Step 6: Final answer
    x = 107.78

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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.