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Finding the Fourth Proportional to 431.80, 647.70 and 215.80

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Solution

The fourth proportional to 431.80, 647.70 and 215.80 is: 323.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.80 : 647.70 = 215.80 : x
  2. Step 2: Convert to fraction form
    431.80/647.70 = 215.80/x
  3. Step 3: Cross multiply
    431.80x = 647.70 × 215.80
  4. Step 4: Simplify right side
    431.80x = 139,773.66
  5. Step 5: Solve for x
    x = 139,773.66/431.80
  6. Step 6: Final answer
    x = 323.70

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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.