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Finding the Fourth Proportional to 99.79, 137.78 and 61

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Solution

The fourth proportional to 99.79, 137.78 and 61 is: 84.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.79 : 137.78 = 61 : x
  2. Step 2: Convert to fraction form
    99.79/137.78 = 61/x
  3. Step 3: Cross multiply
    99.79x = 137.78 × 61
  4. Step 4: Simplify right side
    99.79x = 8,404.58
  5. Step 5: Solve for x
    x = 8,404.58/99.79
  6. Step 6: Final answer
    x = 84.22

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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.