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Finding the Fourth Proportional to 990.88, 1,366.88 and 641.20

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Solution

The fourth proportional to 990.88, 1,366.88 and 641.20 is: 884.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.88 : 1,366.88 = 641.20 : x
  2. Step 2: Convert to fraction form
    990.88/1,366.88 = 641.20/x
  3. Step 3: Cross multiply
    990.88x = 1,366.88 × 641.20
  4. Step 4: Simplify right side
    990.88x = 876,443.46
  5. Step 5: Solve for x
    x = 876,443.46/990.88
  6. Step 6: Final answer
    x = 884.51

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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.