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Finding the Fourth Proportional to 210.31, 290.22 and 121.78

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Solution

The fourth proportional to 210.31, 290.22 and 121.78 is: 168.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.31 : 290.22 = 121.78 : x
  2. Step 2: Convert to fraction form
    210.31/290.22 = 121.78/x
  3. Step 3: Cross multiply
    210.31x = 290.22 × 121.78
  4. Step 4: Simplify right side
    210.31x = 35,342.38
  5. Step 5: Solve for x
    x = 35,342.38/210.31
  6. Step 6: Final answer
    x = 168.05

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.