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Finding the Fourth Proportional to 861.68, 1,290.80 and 422.08

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Solution

The fourth proportional to 861.68, 1,290.80 and 422.08 is: 632.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.68 : 1,290.80 = 422.08 : x
  2. Step 2: Convert to fraction form
    861.68/1,290.80 = 422.08/x
  3. Step 3: Cross multiply
    861.68x = 1,290.80 × 422.08
  4. Step 4: Simplify right side
    861.68x = 544,820.86
  5. Step 5: Solve for x
    x = 544,820.86/861.68
  6. Step 6: Final answer
    x = 632.28

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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.