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Finding the Fourth Proportional to 815.49, 1,123.20 and 640.53

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Solution

The fourth proportional to 815.49, 1,123.20 and 640.53 is: 882.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.49 : 1,123.20 = 640.53 : x
  2. Step 2: Convert to fraction form
    815.49/1,123.20 = 640.53/x
  3. Step 3: Cross multiply
    815.49x = 1,123.20 × 640.53
  4. Step 4: Simplify right side
    815.49x = 719,443.30
  5. Step 5: Solve for x
    x = 719,443.30/815.49
  6. Step 6: Final answer
    x = 882.22

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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.