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Finding the Fourth Proportional to 99.85, 137.81 and 56.20

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Solution

The fourth proportional to 99.85, 137.81 and 56.20 is: 77.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.85 : 137.81 = 56.20 : x
  2. Step 2: Convert to fraction form
    99.85/137.81 = 56.20/x
  3. Step 3: Cross multiply
    99.85x = 137.81 × 56.20
  4. Step 4: Simplify right side
    99.85x = 7,744.92
  5. Step 5: Solve for x
    x = 7,744.92/99.85
  6. Step 6: Final answer
    x = 77.57

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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.