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Finding the Fourth Proportional to 100.62, 138.93 and 85.72

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Solution

The fourth proportional to 100.62, 138.93 and 85.72 is: 118.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.62 : 138.93 = 85.72 : x
  2. Step 2: Convert to fraction form
    100.62/138.93 = 85.72/x
  3. Step 3: Cross multiply
    100.62x = 138.93 × 85.72
  4. Step 4: Simplify right side
    100.62x = 11,909.08
  5. Step 5: Solve for x
    x = 11,909.08/100.62
  6. Step 6: Final answer
    x = 118.36

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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.