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Finding the Fourth Proportional to 861.68, 1,187.52 and 640.28

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Solution

The fourth proportional to 861.68, 1,187.52 and 640.28 is: 882.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.68 : 1,187.52 = 640.28 : x
  2. Step 2: Convert to fraction form
    861.68/1,187.52 = 640.28/x
  3. Step 3: Cross multiply
    861.68x = 1,187.52 × 640.28
  4. Step 4: Simplify right side
    861.68x = 760,345.31
  5. Step 5: Solve for x
    x = 760,345.31/861.68
  6. Step 6: Final answer
    x = 882.40

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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.