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Finding the Fourth Proportional to 100.97, 139.32 and 87.28

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Solution

The fourth proportional to 100.97, 139.32 and 87.28 is: 120.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.97 : 139.32 = 87.28 : x
  2. Step 2: Convert to fraction form
    100.97/139.32 = 87.28/x
  3. Step 3: Cross multiply
    100.97x = 139.32 × 87.28
  4. Step 4: Simplify right side
    100.97x = 12,159.85
  5. Step 5: Solve for x
    x = 12,159.85/100.97
  6. Step 6: Final answer
    x = 120.43

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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.