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Finding the Fourth Proportional to 99.60, 137.37 and 66.78

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Solution

The fourth proportional to 99.60, 137.37 and 66.78 is: 92.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.60 : 137.37 = 66.78 : x
  2. Step 2: Convert to fraction form
    99.60/137.37 = 66.78/x
  3. Step 3: Cross multiply
    99.60x = 137.37 × 66.78
  4. Step 4: Simplify right side
    99.60x = 9,173.57
  5. Step 5: Solve for x
    x = 9,173.57/99.60
  6. Step 6: Final answer
    x = 92.10

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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.