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Finding the Fourth Proportional to 905.89, 1,248.60 and 640.45

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Solution

The fourth proportional to 905.89, 1,248.60 and 640.45 is: 882.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    905.89 : 1,248.60 = 640.45 : x
  2. Step 2: Convert to fraction form
    905.89/1,248.60 = 640.45/x
  3. Step 3: Cross multiply
    905.89x = 1,248.60 × 640.45
  4. Step 4: Simplify right side
    905.89x = 799,665.87
  5. Step 5: Solve for x
    x = 799,665.87/905.89
  6. Step 6: Final answer
    x = 882.74

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.