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Finding the Fourth Proportional to 138, 206.88 and 69.48

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Solution

The fourth proportional to 138, 206.88 and 69.48 is: 104.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    138 : 206.88 = 69.48 : x
  2. Step 2: Convert to fraction form
    138/206.88 = 69.48/x
  3. Step 3: Cross multiply
    138x = 206.88 × 69.48
  4. Step 4: Simplify right side
    138x = 14,374.02
  5. Step 5: Solve for x
    x = 14,374.02/138
  6. Step 6: Final answer
    x = 104.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.