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Finding the Fourth Proportional to 681.68, 1,021.08 and 640.64

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Solution

The fourth proportional to 681.68, 1,021.08 and 640.64 is: 959.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.68 : 1,021.08 = 640.64 : x
  2. Step 2: Convert to fraction form
    681.68/1,021.08 = 640.64/x
  3. Step 3: Cross multiply
    681.68x = 1,021.08 × 640.64
  4. Step 4: Simplify right side
    681.68x = 654,144.69
  5. Step 5: Solve for x
    x = 654,144.69/681.68
  6. Step 6: Final answer
    x = 959.61

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.