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Finding the Fourth Proportional to 906.78, 1,359.26 and 420.18

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Solution

The fourth proportional to 906.78, 1,359.26 and 420.18 is: 629.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    906.78 : 1,359.26 = 420.18 : x
  2. Step 2: Convert to fraction form
    906.78/1,359.26 = 420.18/x
  3. Step 3: Cross multiply
    906.78x = 1,359.26 × 420.18
  4. Step 4: Simplify right side
    906.78x = 571,133.87
  5. Step 5: Solve for x
    x = 571,133.87/906.78
  6. Step 6: Final answer
    x = 629.85

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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.