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Finding the Fourth Proportional to 429.13, 643.74 and 212.86

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Solution

The fourth proportional to 429.13, 643.74 and 212.86 is: 319.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.13 : 643.74 = 212.86 : x
  2. Step 2: Convert to fraction form
    429.13/643.74 = 212.86/x
  3. Step 3: Cross multiply
    429.13x = 643.74 × 212.86
  4. Step 4: Simplify right side
    429.13x = 137,026.50
  5. Step 5: Solve for x
    x = 137,026.50/429.13
  6. Step 6: Final answer
    x = 319.31

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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.