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Finding the Fourth Proportional to 989.52, 1,366 and 640.80

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Solution

The fourth proportional to 989.52, 1,366 and 640.80 is: 884.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.52 : 1,366 = 640.80 : x
  2. Step 2: Convert to fraction form
    989.52/1,366 = 640.80/x
  3. Step 3: Cross multiply
    989.52x = 1,366 × 640.80
  4. Step 4: Simplify right side
    989.52x = 875,332.80
  5. Step 5: Solve for x
    x = 875,332.80/989.52
  6. Step 6: Final answer
    x = 884.60

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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.