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Finding the Fourth Proportional to 86.78, 130.38 and 85.37

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Solution

The fourth proportional to 86.78, 130.38 and 85.37 is: 128.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.78 : 130.38 = 85.37 : x
  2. Step 2: Convert to fraction form
    86.78/130.38 = 85.37/x
  3. Step 3: Cross multiply
    86.78x = 130.38 × 85.37
  4. Step 4: Simplify right side
    86.78x = 11,129.57
  5. Step 5: Solve for x
    x = 11,129.57/86.78
  6. Step 6: Final answer
    x = 128.25

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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.