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Finding the Fourth Proportional to 86.90, 130.34 and 85.55

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Solution

The fourth proportional to 86.90, 130.34 and 85.55 is: 128.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.90 : 130.34 = 85.55 : x
  2. Step 2: Convert to fraction form
    86.90/130.34 = 85.55/x
  3. Step 3: Cross multiply
    86.90x = 130.34 × 85.55
  4. Step 4: Simplify right side
    86.90x = 11,150.15
  5. Step 5: Solve for x
    x = 11,150.15/86.90
  6. Step 6: Final answer
    x = 128.32

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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.