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Finding the Fourth Proportional to 345.31, 518.10 and 128.91

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Solution

The fourth proportional to 345.31, 518.10 and 128.91 is: 193.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    345.31 : 518.10 = 128.91 : x
  2. Step 2: Convert to fraction form
    345.31/518.10 = 128.91/x
  3. Step 3: Cross multiply
    345.31x = 518.10 × 128.91
  4. Step 4: Simplify right side
    345.31x = 66,786.81
  5. Step 5: Solve for x
    x = 66,786.81/345.31
  6. Step 6: Final answer
    x = 193.41

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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.