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Finding the Fourth Proportional to 639.40, 881.61 and 513.26

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Solution

The fourth proportional to 639.40, 881.61 and 513.26 is: 707.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.40 : 881.61 = 513.26 : x
  2. Step 2: Convert to fraction form
    639.40/881.61 = 513.26/x
  3. Step 3: Cross multiply
    639.40x = 881.61 × 513.26
  4. Step 4: Simplify right side
    639.40x = 452,495.15
  5. Step 5: Solve for x
    x = 452,495.15/639.40
  6. Step 6: Final answer
    x = 707.69

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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.