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Finding the Fourth Proportional to 100.65, 138.86 and 61.29

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Solution

The fourth proportional to 100.65, 138.86 and 61.29 is: 84.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.65 : 138.86 = 61.29 : x
  2. Step 2: Convert to fraction form
    100.65/138.86 = 61.29/x
  3. Step 3: Cross multiply
    100.65x = 138.86 × 61.29
  4. Step 4: Simplify right side
    100.65x = 8,510.16
  5. Step 5: Solve for x
    x = 8,510.16/100.65
  6. Step 6: Final answer
    x = 84.56

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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.