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Finding the Fourth Proportional to 100.82, 139.38 and 87.14

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Solution

The fourth proportional to 100.82, 139.38 and 87.14 is: 120.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.82 : 139.38 = 87.14 : x
  2. Step 2: Convert to fraction form
    100.82/139.38 = 87.14/x
  3. Step 3: Cross multiply
    100.82x = 139.38 × 87.14
  4. Step 4: Simplify right side
    100.82x = 12,145.57
  5. Step 5: Solve for x
    x = 12,145.57/100.82
  6. Step 6: Final answer
    x = 120.47

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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.