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Finding the Fourth Proportional to 861.32, 1,187.82 and 640.76

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Solution

The fourth proportional to 861.32, 1,187.82 and 640.76 is: 883.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.32 : 1,187.82 = 640.76 : x
  2. Step 2: Convert to fraction form
    861.32/1,187.82 = 640.76/x
  3. Step 3: Cross multiply
    861.32x = 1,187.82 × 640.76
  4. Step 4: Simplify right side
    861.32x = 761,107.54
  5. Step 5: Solve for x
    x = 761,107.54/861.32
  6. Step 6: Final answer
    x = 883.65

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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.