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Finding the Fourth Proportional to 816.81, 1,125.87 and 639.47

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Solution

The fourth proportional to 816.81, 1,125.87 and 639.47 is: 881.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.81 : 1,125.87 = 639.47 : x
  2. Step 2: Convert to fraction form
    816.81/1,125.87 = 639.47/x
  3. Step 3: Cross multiply
    816.81x = 1,125.87 × 639.47
  4. Step 4: Simplify right side
    816.81x = 719,954.46
  5. Step 5: Solve for x
    x = 719,954.46/816.81
  6. Step 6: Final answer
    x = 881.42

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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.