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Finding the Fourth Proportional to 839.16, 1,257.64 and 428.40

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Solution

The fourth proportional to 839.16, 1,257.64 and 428.40 is: 642.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.16 : 1,257.64 = 428.40 : x
  2. Step 2: Convert to fraction form
    839.16/1,257.64 = 428.40/x
  3. Step 3: Cross multiply
    839.16x = 1,257.64 × 428.40
  4. Step 4: Simplify right side
    839.16x = 538,772.98
  5. Step 5: Solve for x
    x = 538,772.98/839.16
  6. Step 6: Final answer
    x = 642.04

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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.