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Finding the Fourth Proportional to 718.56, 991.61 and 403.78

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Solution

The fourth proportional to 718.56, 991.61 and 403.78 is: 557.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.56 : 991.61 = 403.78 : x
  2. Step 2: Convert to fraction form
    718.56/991.61 = 403.78/x
  3. Step 3: Cross multiply
    718.56x = 991.61 × 403.78
  4. Step 4: Simplify right side
    718.56x = 400,392.29
  5. Step 5: Solve for x
    x = 400,392.29/718.56
  6. Step 6: Final answer
    x = 557.21

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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.