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Finding the Fourth Proportional to 857.28, 1,285.65 and 309.39

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Solution

The fourth proportional to 857.28, 1,285.65 and 309.39 is: 463.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.28 : 1,285.65 = 309.39 : x
  2. Step 2: Convert to fraction form
    857.28/1,285.65 = 309.39/x
  3. Step 3: Cross multiply
    857.28x = 1,285.65 × 309.39
  4. Step 4: Simplify right side
    857.28x = 397,759.28
  5. Step 5: Solve for x
    x = 397,759.28/857.28
  6. Step 6: Final answer
    x = 463.98

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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.