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Finding the Fourth Proportional to 860.72, 1,187.92 and 639.36

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Solution

The fourth proportional to 860.72, 1,187.92 and 639.36 is: 882.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.72 : 1,187.92 = 639.36 : x
  2. Step 2: Convert to fraction form
    860.72/1,187.92 = 639.36/x
  3. Step 3: Cross multiply
    860.72x = 1,187.92 × 639.36
  4. Step 4: Simplify right side
    860.72x = 759,508.53
  5. Step 5: Solve for x
    x = 759,508.53/860.72
  6. Step 6: Final answer
    x = 882.41

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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.