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Finding the Fourth Proportional to 121.72, 181.33 and 115.91

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Solution

The fourth proportional to 121.72, 181.33 and 115.91 is: 172.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.72 : 181.33 = 115.91 : x
  2. Step 2: Convert to fraction form
    121.72/181.33 = 115.91/x
  3. Step 3: Cross multiply
    121.72x = 181.33 × 115.91
  4. Step 4: Simplify right side
    121.72x = 21,017.38
  5. Step 5: Solve for x
    x = 21,017.38/121.72
  6. Step 6: Final answer
    x = 172.68

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.