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Finding the Fourth Proportional to 861.06, 1,290.42 and 428.52

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Solution

The fourth proportional to 861.06, 1,290.42 and 428.52 is: 642.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.06 : 1,290.42 = 428.52 : x
  2. Step 2: Convert to fraction form
    861.06/1,290.42 = 428.52/x
  3. Step 3: Cross multiply
    861.06x = 1,290.42 × 428.52
  4. Step 4: Simplify right side
    861.06x = 552,970.78
  5. Step 5: Solve for x
    x = 552,970.78/861.06
  6. Step 6: Final answer
    x = 642.20

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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.