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Finding the Fourth Proportional to 100, 138.18 and 87.04

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Solution

The fourth proportional to 100, 138.18 and 87.04 is: 120.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    100 : 138.18 = 87.04 : x
  2. Step 2: Convert to fraction form
    100/138.18 = 87.04/x
  3. Step 3: Cross multiply
    100x = 138.18 × 87.04
  4. Step 4: Simplify right side
    100x = 12,027.19
  5. Step 5: Solve for x
    x = 12,027.19/100
  6. Step 6: Final answer
    x = 120.27

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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.