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Finding the Fourth Proportional to 1,081.62, 1,491.95 and 639.21

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Solution

The fourth proportional to 1,081.62, 1,491.95 and 639.21 is: 881.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,081.62 : 1,491.95 = 639.21 : x
  2. Step 2: Convert to fraction form
    1,081.62/1,491.95 = 639.21/x
  3. Step 3: Cross multiply
    1,081.62x = 1,491.95 × 639.21
  4. Step 4: Simplify right side
    1,081.62x = 953,669.36
  5. Step 5: Solve for x
    x = 953,669.36/1,081.62
  6. Step 6: Final answer
    x = 881.70

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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.