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Finding the Fourth Proportional to 775.80, 1,069.74 and 642.60

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Solution

The fourth proportional to 775.80, 1,069.74 and 642.60 is: 886.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    775.80 : 1,069.74 = 642.60 : x
  2. Step 2: Convert to fraction form
    775.80/1,069.74 = 642.60/x
  3. Step 3: Cross multiply
    775.80x = 1,069.74 × 642.60
  4. Step 4: Simplify right side
    775.80x = 687,414.92
  5. Step 5: Solve for x
    x = 687,414.92/775.80
  6. Step 6: Final answer
    x = 886.07

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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.