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Finding the Fourth Proportional to 611.31, 843.74 and 390.21

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Solution

The fourth proportional to 611.31, 843.74 and 390.21 is: 538.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.31 : 843.74 = 390.21 : x
  2. Step 2: Convert to fraction form
    611.31/843.74 = 390.21/x
  3. Step 3: Cross multiply
    611.31x = 843.74 × 390.21
  4. Step 4: Simplify right side
    611.31x = 329,235.79
  5. Step 5: Solve for x
    x = 329,235.79/611.31
  6. Step 6: Final answer
    x = 538.57

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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.