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Finding the Fourth Proportional to 100.65, 138.92 and 63.78

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Solution

The fourth proportional to 100.65, 138.92 and 63.78 is: 88.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.65 : 138.92 = 63.78 : x
  2. Step 2: Convert to fraction form
    100.65/138.92 = 63.78/x
  3. Step 3: Cross multiply
    100.65x = 138.92 × 63.78
  4. Step 4: Simplify right side
    100.65x = 8,860.32
  5. Step 5: Solve for x
    x = 8,860.32/100.65
  6. Step 6: Final answer
    x = 88.03

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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.