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Finding the Fourth Proportional to 717.98, 990.78 and 403.21

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Solution

The fourth proportional to 717.98, 990.78 and 403.21 is: 556.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    717.98 : 990.78 = 403.21 : x
  2. Step 2: Convert to fraction form
    717.98/990.78 = 403.21/x
  3. Step 3: Cross multiply
    717.98x = 990.78 × 403.21
  4. Step 4: Simplify right side
    717.98x = 399,486.56
  5. Step 5: Solve for x
    x = 399,486.56/717.98
  6. Step 6: Final answer
    x = 556.40

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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.