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Finding the Fourth Proportional to 100.87, 139.04 and 71.71

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Solution

The fourth proportional to 100.87, 139.04 and 71.71 is: 98.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.87 : 139.04 = 71.71 : x
  2. Step 2: Convert to fraction form
    100.87/139.04 = 71.71/x
  3. Step 3: Cross multiply
    100.87x = 139.04 × 71.71
  4. Step 4: Simplify right side
    100.87x = 9,969.86
  5. Step 5: Solve for x
    x = 9,969.86/100.87
  6. Step 6: Final answer
    x = 98.84

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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.