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Finding the Fourth Proportional to 839.31, 1,259.75 and 428.74

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Solution

The fourth proportional to 839.31, 1,259.75 and 428.74 is: 643.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.31 : 1,259.75 = 428.74 : x
  2. Step 2: Convert to fraction form
    839.31/1,259.75 = 428.74/x
  3. Step 3: Cross multiply
    839.31x = 1,259.75 × 428.74
  4. Step 4: Simplify right side
    839.31x = 540,096.77
  5. Step 5: Solve for x
    x = 540,096.77/839.31
  6. Step 6: Final answer
    x = 643.50

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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.