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Finding the Fourth Proportional to 99.68, 137.42 and 77.80

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Solution

The fourth proportional to 99.68, 137.42 and 77.80 is: 107.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.68 : 137.42 = 77.80 : x
  2. Step 2: Convert to fraction form
    99.68/137.42 = 77.80/x
  3. Step 3: Cross multiply
    99.68x = 137.42 × 77.80
  4. Step 4: Simplify right side
    99.68x = 10,691.28
  5. Step 5: Solve for x
    x = 10,691.28/99.68
  6. Step 6: Final answer
    x = 107.26

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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.