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Finding the Fourth Proportional to 971.55, 1,339.83 and 639.66

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Solution

The fourth proportional to 971.55, 1,339.83 and 639.66 is: 882.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.55 : 1,339.83 = 639.66 : x
  2. Step 2: Convert to fraction form
    971.55/1,339.83 = 639.66/x
  3. Step 3: Cross multiply
    971.55x = 1,339.83 × 639.66
  4. Step 4: Simplify right side
    971.55x = 857,035.66
  5. Step 5: Solve for x
    x = 857,035.66/971.55
  6. Step 6: Final answer
    x = 882.13

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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.