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Finding the Fourth Proportional to 1,272.90, 1,909.37 and 407.21

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Solution

The fourth proportional to 1,272.90, 1,909.37 and 407.21 is: 610.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,272.90 : 1,909.37 = 407.21 : x
  2. Step 2: Convert to fraction form
    1,272.90/1,909.37 = 407.21/x
  3. Step 3: Cross multiply
    1,272.90x = 1,909.37 × 407.21
  4. Step 4: Simplify right side
    1,272.90x = 777,511.66
  5. Step 5: Solve for x
    x = 777,511.66/1,272.90
  6. Step 6: Final answer
    x = 610.82

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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.