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Finding the Fourth Proportional to 718.45, 991.47 and 399.45

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Solution

The fourth proportional to 718.45, 991.47 and 399.45 is: 551.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.45 : 991.47 = 399.45 : x
  2. Step 2: Convert to fraction form
    718.45/991.47 = 399.45/x
  3. Step 3: Cross multiply
    718.45x = 991.47 × 399.45
  4. Step 4: Simplify right side
    718.45x = 396,037.73
  5. Step 5: Solve for x
    x = 396,037.73/718.45
  6. Step 6: Final answer
    x = 551.24

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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.