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Finding the Fourth Proportional to 99.70, 137.72 and 78.16

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Solution

The fourth proportional to 99.70, 137.72 and 78.16 is: 107.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.70 : 137.72 = 78.16 : x
  2. Step 2: Convert to fraction form
    99.70/137.72 = 78.16/x
  3. Step 3: Cross multiply
    99.70x = 137.72 × 78.16
  4. Step 4: Simplify right side
    99.70x = 10,764.20
  5. Step 5: Solve for x
    x = 10,764.20/99.70
  6. Step 6: Final answer
    x = 107.97

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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.