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Finding the Fourth Proportional to 718.78, 991.84 and 399.76

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Solution

The fourth proportional to 718.78, 991.84 and 399.76 is: 551.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.78 : 991.84 = 399.76 : x
  2. Step 2: Convert to fraction form
    718.78/991.84 = 399.76/x
  3. Step 3: Cross multiply
    718.78x = 991.84 × 399.76
  4. Step 4: Simplify right side
    718.78x = 396,497.96
  5. Step 5: Solve for x
    x = 396,497.96/718.78
  6. Step 6: Final answer
    x = 551.63

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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.