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Finding the Fourth Proportional to 686.51, 1,024.79 and 640.40

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Solution

The fourth proportional to 686.51, 1,024.79 and 640.40 is: 955.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.51 : 1,024.79 = 640.40 : x
  2. Step 2: Convert to fraction form
    686.51/1,024.79 = 640.40/x
  3. Step 3: Cross multiply
    686.51x = 1,024.79 × 640.40
  4. Step 4: Simplify right side
    686.51x = 656,275.52
  5. Step 5: Solve for x
    x = 656,275.52/686.51
  6. Step 6: Final answer
    x = 955.97

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.