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Finding the Fourth Proportional to 815.17, 1,123.69 and 640.21

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Solution

The fourth proportional to 815.17, 1,123.69 and 640.21 is: 882.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.17 : 1,123.69 = 640.21 : x
  2. Step 2: Convert to fraction form
    815.17/1,123.69 = 640.21/x
  3. Step 3: Cross multiply
    815.17x = 1,123.69 × 640.21
  4. Step 4: Simplify right side
    815.17x = 719,397.57
  5. Step 5: Solve for x
    x = 719,397.57/815.17
  6. Step 6: Final answer
    x = 882.51

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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.