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Finding the Fourth Proportional to 137.82, 206.40 and 86.28

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Solution

The fourth proportional to 137.82, 206.40 and 86.28 is: 129.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.82 : 206.40 = 86.28 : x
  2. Step 2: Convert to fraction form
    137.82/206.40 = 86.28/x
  3. Step 3: Cross multiply
    137.82x = 206.40 × 86.28
  4. Step 4: Simplify right side
    137.82x = 17,808.19
  5. Step 5: Solve for x
    x = 17,808.19/137.82
  6. Step 6: Final answer
    x = 129.21

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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.