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Finding the Fourth Proportional to 120.61, 180.50 and 86.45

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Solution

The fourth proportional to 120.61, 180.50 and 86.45 is: 129.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.61 : 180.50 = 86.45 : x
  2. Step 2: Convert to fraction form
    120.61/180.50 = 86.45/x
  3. Step 3: Cross multiply
    120.61x = 180.50 × 86.45
  4. Step 4: Simplify right side
    120.61x = 15,602.89
  5. Step 5: Solve for x
    x = 15,602.89/120.61
  6. Step 6: Final answer
    x = 129.37

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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.