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Finding the Fourth Proportional to 100.76, 139.05 and 86.99

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Solution

The fourth proportional to 100.76, 139.05 and 86.99 is: 120.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.76 : 139.05 = 86.99 : x
  2. Step 2: Convert to fraction form
    100.76/139.05 = 86.99/x
  3. Step 3: Cross multiply
    100.76x = 139.05 × 86.99
  4. Step 4: Simplify right side
    100.76x = 12,095.26
  5. Step 5: Solve for x
    x = 12,095.26/100.76
  6. Step 6: Final answer
    x = 120.05

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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.