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Finding the Fourth Proportional to 971.48, 1,339.72 and 639.76

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Solution

The fourth proportional to 971.48, 1,339.72 and 639.76 is: 882.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.48 : 1,339.72 = 639.76 : x
  2. Step 2: Convert to fraction form
    971.48/1,339.72 = 639.76/x
  3. Step 3: Cross multiply
    971.48x = 1,339.72 × 639.76
  4. Step 4: Simplify right side
    971.48x = 857,099.27
  5. Step 5: Solve for x
    x = 857,099.27/971.48
  6. Step 6: Final answer
    x = 882.26

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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.