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Finding the Fourth Proportional to 135.40, 186.75 and 86.21

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Solution

The fourth proportional to 135.40, 186.75 and 86.21 is: 118.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    135.40 : 186.75 = 86.21 : x
  2. Step 2: Convert to fraction form
    135.40/186.75 = 86.21/x
  3. Step 3: Cross multiply
    135.40x = 186.75 × 86.21
  4. Step 4: Simplify right side
    135.40x = 16,099.72
  5. Step 5: Solve for x
    x = 16,099.72/135.40
  6. Step 6: Final answer
    x = 118.90

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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.