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Finding the Fourth Proportional to 99.90, 137.70 and 78.03

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Solution

The fourth proportional to 99.90, 137.70 and 78.03 is: 107.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.90 : 137.70 = 78.03 : x
  2. Step 2: Convert to fraction form
    99.90/137.70 = 78.03/x
  3. Step 3: Cross multiply
    99.90x = 137.70 × 78.03
  4. Step 4: Simplify right side
    99.90x = 10,744.73
  5. Step 5: Solve for x
    x = 10,744.73/99.90
  6. Step 6: Final answer
    x = 107.55

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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.