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Finding the Fourth Proportional to 857.60, 1,285.12 and 641.28

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Solution

The fourth proportional to 857.60, 1,285.12 and 641.28 is: 960.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.60 : 1,285.12 = 641.28 : x
  2. Step 2: Convert to fraction form
    857.60/1,285.12 = 641.28/x
  3. Step 3: Cross multiply
    857.60x = 1,285.12 × 641.28
  4. Step 4: Simplify right side
    857.60x = 824,121.75
  5. Step 5: Solve for x
    x = 824,121.75/857.60
  6. Step 6: Final answer
    x = 960.96

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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.