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Finding the Fourth Proportional to 1,069.60, 1,604.80 and 420.78

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Solution

The fourth proportional to 1,069.60, 1,604.80 and 420.78 is: 631.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,069.60 : 1,604.80 = 420.78 : x
  2. Step 2: Convert to fraction form
    1,069.60/1,604.80 = 420.78/x
  3. Step 3: Cross multiply
    1,069.60x = 1,604.80 × 420.78
  4. Step 4: Simplify right side
    1,069.60x = 675,267.74
  5. Step 5: Solve for x
    x = 675,267.74/1,069.60
  6. Step 6: Final answer
    x = 631.33

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.