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Finding the Fourth Proportional to 120.69, 180.78 and 72.57

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Solution

The fourth proportional to 120.69, 180.78 and 72.57 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.69 : 180.78 = 72.57 : x
  2. Step 2: Convert to fraction form
    120.69/180.78 = 72.57/x
  3. Step 3: Cross multiply
    120.69x = 180.78 × 72.57
  4. Step 4: Simplify right side
    120.69x = 13,117.94
  5. Step 5: Solve for x
    x = 13,117.94/120.69
  6. Step 6: Final answer
    x = 108.70

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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.