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Finding the Fourth Proportional to 681.60, 1,027.20 and 638.40

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Solution

The fourth proportional to 681.60, 1,027.20 and 638.40 is: 962.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.60 : 1,027.20 = 638.40 : x
  2. Step 2: Convert to fraction form
    681.60/1,027.20 = 638.40/x
  3. Step 3: Cross multiply
    681.60x = 1,027.20 × 638.40
  4. Step 4: Simplify right side
    681.60x = 655,764.48
  5. Step 5: Solve for x
    x = 655,764.48/681.60
  6. Step 6: Final answer
    x = 962.10

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.