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Finding the Fourth Proportional to 971.65, 1,339.63 and 639.55

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Solution

The fourth proportional to 971.65, 1,339.63 and 639.55 is: 881.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.65 : 1,339.63 = 639.55 : x
  2. Step 2: Convert to fraction form
    971.65/1,339.63 = 639.55/x
  3. Step 3: Cross multiply
    971.65x = 1,339.63 × 639.55
  4. Step 4: Simplify right side
    971.65x = 856,760.37
  5. Step 5: Solve for x
    x = 856,760.37/971.65
  6. Step 6: Final answer
    x = 881.76

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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.