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Finding the Fourth Proportional to 135.90, 187.40 and 86.78

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Solution

The fourth proportional to 135.90, 187.40 and 86.78 is: 119.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    135.90 : 187.40 = 86.78 : x
  2. Step 2: Convert to fraction form
    135.90/187.40 = 86.78/x
  3. Step 3: Cross multiply
    135.90x = 187.40 × 86.78
  4. Step 4: Simplify right side
    135.90x = 16,262.57
  5. Step 5: Solve for x
    x = 16,262.57/135.90
  6. Step 6: Final answer
    x = 119.67

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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.