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Finding the Fourth Proportional to 100.57, 138.67 and 85.79

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Solution

The fourth proportional to 100.57, 138.67 and 85.79 is: 118.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.57 : 138.67 = 85.79 : x
  2. Step 2: Convert to fraction form
    100.57/138.67 = 85.79/x
  3. Step 3: Cross multiply
    100.57x = 138.67 × 85.79
  4. Step 4: Simplify right side
    100.57x = 11,896.50
  5. Step 5: Solve for x
    x = 11,896.50/100.57
  6. Step 6: Final answer
    x = 118.29

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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.