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Finding the Fourth Proportional to 853.89, 1,280.63 and 420.95

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Solution

The fourth proportional to 853.89, 1,280.63 and 420.95 is: 631.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.89 : 1,280.63 = 420.95 : x
  2. Step 2: Convert to fraction form
    853.89/1,280.63 = 420.95/x
  3. Step 3: Cross multiply
    853.89x = 1,280.63 × 420.95
  4. Step 4: Simplify right side
    853.89x = 539,072.69
  5. Step 5: Solve for x
    x = 539,072.69/853.89
  6. Step 6: Final answer
    x = 631.31

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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.