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Finding the Fourth Proportional to 775.28, 1,069.88 and 421.21

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Solution

The fourth proportional to 775.28, 1,069.88 and 421.21 is: 581.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    775.28 : 1,069.88 = 421.21 : x
  2. Step 2: Convert to fraction form
    775.28/1,069.88 = 421.21/x
  3. Step 3: Cross multiply
    775.28x = 1,069.88 × 421.21
  4. Step 4: Simplify right side
    775.28x = 450,637.75
  5. Step 5: Solve for x
    x = 450,637.75/775.28
  6. Step 6: Final answer
    x = 581.26

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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.