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Finding the Fourth Proportional to 773.69, 1,065.40 and 639.92

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Solution

The fourth proportional to 773.69, 1,065.40 and 639.92 is: 881.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    773.69 : 1,065.40 = 639.92 : x
  2. Step 2: Convert to fraction form
    773.69/1,065.40 = 639.92/x
  3. Step 3: Cross multiply
    773.69x = 1,065.40 × 639.92
  4. Step 4: Simplify right side
    773.69x = 681,771.83
  5. Step 5: Solve for x
    x = 681,771.83/773.69
  6. Step 6: Final answer
    x = 881.20

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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.