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Finding the Fourth Proportional to 861.78, 1,189.41 and 488.76

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Solution

The fourth proportional to 861.78, 1,189.41 and 488.76 is: 674.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.78 : 1,189.41 = 488.76 : x
  2. Step 2: Convert to fraction form
    861.78/1,189.41 = 488.76/x
  3. Step 3: Cross multiply
    861.78x = 1,189.41 × 488.76
  4. Step 4: Simplify right side
    861.78x = 581,336.03
  5. Step 5: Solve for x
    x = 581,336.03/861.78
  6. Step 6: Final answer
    x = 674.58

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1.5x scale

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.