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Finding the Fourth Proportional to 861.40, 1,188.78 and 488.24

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Solution

The fourth proportional to 861.40, 1,188.78 and 488.24 is: 673.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.40 : 1,188.78 = 488.24 : x
  2. Step 2: Convert to fraction form
    861.40/1,188.78 = 488.24/x
  3. Step 3: Cross multiply
    861.40x = 1,188.78 × 488.24
  4. Step 4: Simplify right side
    861.40x = 580,409.95
  5. Step 5: Solve for x
    x = 580,409.95/861.40
  6. Step 6: Final answer
    x = 673.80

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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.