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Finding the Fourth Proportional to 786.72, 1,085.22 and 639.48

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Solution

The fourth proportional to 786.72, 1,085.22 and 639.48 is: 882.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.72 : 1,085.22 = 639.48 : x
  2. Step 2: Convert to fraction form
    786.72/1,085.22 = 639.48/x
  3. Step 3: Cross multiply
    786.72x = 1,085.22 × 639.48
  4. Step 4: Simplify right side
    786.72x = 693,976.49
  5. Step 5: Solve for x
    x = 693,976.49/786.72
  6. Step 6: Final answer
    x = 882.11

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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.