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Finding the Fourth Proportional to 121.47, 181.75 and 72.78

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Solution

The fourth proportional to 121.47, 181.75 and 72.78 is: 108.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.47 : 181.75 = 72.78 : x
  2. Step 2: Convert to fraction form
    121.47/181.75 = 72.78/x
  3. Step 3: Cross multiply
    121.47x = 181.75 × 72.78
  4. Step 4: Simplify right side
    121.47x = 13,227.77
  5. Step 5: Solve for x
    x = 13,227.77/121.47
  6. Step 6: Final answer
    x = 108.90

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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.