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Finding the Fourth Proportional to 100.60, 138.47 and 87.64

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Solution

The fourth proportional to 100.60, 138.47 and 87.64 is: 120.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.60 : 138.47 = 87.64 : x
  2. Step 2: Convert to fraction form
    100.60/138.47 = 87.64/x
  3. Step 3: Cross multiply
    100.60x = 138.47 × 87.64
  4. Step 4: Simplify right side
    100.60x = 12,134.82
  5. Step 5: Solve for x
    x = 12,134.82/100.60
  6. Step 6: Final answer
    x = 120.63

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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.