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Finding the Fourth Proportional to 989.91, 1,366.38 and 640.53

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Solution

The fourth proportional to 989.91, 1,366.38 and 640.53 is: 884.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.91 : 1,366.38 = 640.53 : x
  2. Step 2: Convert to fraction form
    989.91/1,366.38 = 640.53/x
  3. Step 3: Cross multiply
    989.91x = 1,366.38 × 640.53
  4. Step 4: Simplify right side
    989.91x = 875,207.38
  5. Step 5: Solve for x
    x = 875,207.38/989.91
  6. Step 6: Final answer
    x = 884.13

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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.