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Finding the Fourth Proportional to 100.62, 138.84 and 85.74

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Solution

The fourth proportional to 100.62, 138.84 and 85.74 is: 118.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.62 : 138.84 = 85.74 : x
  2. Step 2: Convert to fraction form
    100.62/138.84 = 85.74/x
  3. Step 3: Cross multiply
    100.62x = 138.84 × 85.74
  4. Step 4: Simplify right side
    100.62x = 11,904.14
  5. Step 5: Solve for x
    x = 11,904.14/100.62
  6. Step 6: Final answer
    x = 118.31

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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.