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Finding the Fourth Proportional to 100.23, 138.68 and 87.32

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Solution

The fourth proportional to 100.23, 138.68 and 87.32 is: 120.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.23 : 138.68 = 87.32 : x
  2. Step 2: Convert to fraction form
    100.23/138.68 = 87.32/x
  3. Step 3: Cross multiply
    100.23x = 138.68 × 87.32
  4. Step 4: Simplify right side
    100.23x = 12,108.41
  5. Step 5: Solve for x
    x = 12,108.41/100.23
  6. Step 6: Final answer
    x = 120.81

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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.