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Finding the Fourth Proportional to 100.56, 138.79 and 61.75

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Solution

The fourth proportional to 100.56, 138.79 and 61.75 is: 85.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.56 : 138.79 = 61.75 : x
  2. Step 2: Convert to fraction form
    100.56/138.79 = 61.75/x
  3. Step 3: Cross multiply
    100.56x = 138.79 × 61.75
  4. Step 4: Simplify right side
    100.56x = 8,570.28
  5. Step 5: Solve for x
    x = 8,570.28/100.56
  6. Step 6: Final answer
    x = 85.23

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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.