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Finding the Fourth Proportional to 971.28, 1,339.79 and 639.59

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Solution

The fourth proportional to 971.28, 1,339.79 and 639.59 is: 882.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.28 : 1,339.79 = 639.59 : x
  2. Step 2: Convert to fraction form
    971.28/1,339.79 = 639.59/x
  3. Step 3: Cross multiply
    971.28x = 1,339.79 × 639.59
  4. Step 4: Simplify right side
    971.28x = 856,906.39
  5. Step 5: Solve for x
    x = 856,906.39/971.28
  6. Step 6: Final answer
    x = 882.24

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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.