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Finding the Fourth Proportional to 137.70, 189.98 and 78.69

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Solution

The fourth proportional to 137.70, 189.98 and 78.69 is: 108.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.70 : 189.98 = 78.69 : x
  2. Step 2: Convert to fraction form
    137.70/189.98 = 78.69/x
  3. Step 3: Cross multiply
    137.70x = 189.98 × 78.69
  4. Step 4: Simplify right side
    137.70x = 14,949.53
  5. Step 5: Solve for x
    x = 14,949.53/137.70
  6. Step 6: Final answer
    x = 108.57

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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.