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Finding the Fourth Proportional to 787.32, 1,085.40 and 638.28

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Solution

The fourth proportional to 787.32, 1,085.40 and 638.28 is: 879.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.32 : 1,085.40 = 638.28 : x
  2. Step 2: Convert to fraction form
    787.32/1,085.40 = 638.28/x
  3. Step 3: Cross multiply
    787.32x = 1,085.40 × 638.28
  4. Step 4: Simplify right side
    787.32x = 692,789.11
  5. Step 5: Solve for x
    x = 692,789.11/787.32
  6. Step 6: Final answer
    x = 879.93

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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.