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Finding the Fourth Proportional to 816.18, 1,127.79 and 639.60

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Solution

The fourth proportional to 816.18, 1,127.79 and 639.60 is: 883.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.18 : 1,127.79 = 639.60 : x
  2. Step 2: Convert to fraction form
    816.18/1,127.79 = 639.60/x
  3. Step 3: Cross multiply
    816.18x = 1,127.79 × 639.60
  4. Step 4: Simplify right side
    816.18x = 721,334.48
  5. Step 5: Solve for x
    x = 721,334.48/816.18
  6. Step 6: Final answer
    x = 883.79

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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.