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Finding the Fourth Proportional to 1,011.36, 1,396.56 and 639

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Solution

The fourth proportional to 1,011.36, 1,396.56 and 639 is: 882.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,011.36 : 1,396.56 = 639 : x
  2. Step 2: Convert to fraction form
    1,011.36/1,396.56 = 639/x
  3. Step 3: Cross multiply
    1,011.36x = 1,396.56 × 639
  4. Step 4: Simplify right side
    1,011.36x = 892,401.84
  5. Step 5: Solve for x
    x = 892,401.84/1,011.36
  6. Step 6: Final answer
    x = 882.38

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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.