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Finding the Fourth Proportional to 99.99, 137.90 and 77.81

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Solution

The fourth proportional to 99.99, 137.90 and 77.81 is: 107.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.99 : 137.90 = 77.81 : x
  2. Step 2: Convert to fraction form
    99.99/137.90 = 77.81/x
  3. Step 3: Cross multiply
    99.99x = 137.90 × 77.81
  4. Step 4: Simplify right side
    99.99x = 10,728.92
  5. Step 5: Solve for x
    x = 10,728.92/99.99
  6. Step 6: Final answer
    x = 107.30

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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.