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Finding the Fourth Proportional to 640.40, 883.56 and 391.66

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Solution

The fourth proportional to 640.40, 883.56 and 391.66 is: 540.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.40 : 883.56 = 391.66 : x
  2. Step 2: Convert to fraction form
    640.40/883.56 = 391.66/x
  3. Step 3: Cross multiply
    640.40x = 883.56 × 391.66
  4. Step 4: Simplify right side
    640.40x = 346,055.11
  5. Step 5: Solve for x
    x = 346,055.11/640.40
  6. Step 6: Final answer
    x = 540.37

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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.