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Finding the Fourth Proportional to 726.80, 1,089.78 and 640.32

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Solution

The fourth proportional to 726.80, 1,089.78 and 640.32 is: 960.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    726.80 : 1,089.78 = 640.32 : x
  2. Step 2: Convert to fraction form
    726.80/1,089.78 = 640.32/x
  3. Step 3: Cross multiply
    726.80x = 1,089.78 × 640.32
  4. Step 4: Simplify right side
    726.80x = 697,807.93
  5. Step 5: Solve for x
    x = 697,807.93/726.80
  6. Step 6: Final answer
    x = 960.12

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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.