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Finding the Fourth Proportional to 101.60, 139.85 and 87.70

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Solution

The fourth proportional to 101.60, 139.85 and 87.70 is: 120.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.60 : 139.85 = 87.70 : x
  2. Step 2: Convert to fraction form
    101.60/139.85 = 87.70/x
  3. Step 3: Cross multiply
    101.60x = 139.85 × 87.70
  4. Step 4: Simplify right side
    101.60x = 12,264.15
  5. Step 5: Solve for x
    x = 12,264.15/101.60
  6. Step 6: Final answer
    x = 120.72

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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.