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Finding the Fourth Proportional to 839.70, 1,258.98 and 428.04

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Solution

The fourth proportional to 839.70, 1,258.98 and 428.04 is: 641.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.70 : 1,258.98 = 428.04 : x
  2. Step 2: Convert to fraction form
    839.70/1,258.98 = 428.04/x
  3. Step 3: Cross multiply
    839.70x = 1,258.98 × 428.04
  4. Step 4: Simplify right side
    839.70x = 538,893.80
  5. Step 5: Solve for x
    x = 538,893.80/839.70
  6. Step 6: Final answer
    x = 641.77

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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.