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Finding the Fourth Proportional to 859.21, 1,288.85 and 420.39

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Solution

The fourth proportional to 859.21, 1,288.85 and 420.39 is: 630.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.21 : 1,288.85 = 420.39 : x
  2. Step 2: Convert to fraction form
    859.21/1,288.85 = 420.39/x
  3. Step 3: Cross multiply
    859.21x = 1,288.85 × 420.39
  4. Step 4: Simplify right side
    859.21x = 541,817.55
  5. Step 5: Solve for x
    x = 541,817.55/859.21
  6. Step 6: Final answer
    x = 630.60

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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.