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Finding the Fourth Proportional to 100.64, 138.72 and 67.88

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Solution

The fourth proportional to 100.64, 138.72 and 67.88 is: 93.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.64 : 138.72 = 67.88 : x
  2. Step 2: Convert to fraction form
    100.64/138.72 = 67.88/x
  3. Step 3: Cross multiply
    100.64x = 138.72 × 67.88
  4. Step 4: Simplify right side
    100.64x = 9,416.31
  5. Step 5: Solve for x
    x = 9,416.31/100.64
  6. Step 6: Final answer
    x = 93.56

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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.