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Finding the Fourth Proportional to 861.42, 1,188.84 and 721.29

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Solution

The fourth proportional to 861.42, 1,188.84 and 721.29 is: 995.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.42 : 1,188.84 = 721.29 : x
  2. Step 2: Convert to fraction form
    861.42/1,188.84 = 721.29/x
  3. Step 3: Cross multiply
    861.42x = 1,188.84 × 721.29
  4. Step 4: Simplify right side
    861.42x = 857,498.40
  5. Step 5: Solve for x
    x = 857,498.40/861.42
  6. Step 6: Final answer
    x = 995.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.