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Finding the Fourth Proportional to 718.02, 990.81 and 399

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Solution

The fourth proportional to 718.02, 990.81 and 399 is: 550.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.02 : 990.81 = 399 : x
  2. Step 2: Convert to fraction form
    718.02/990.81 = 399/x
  3. Step 3: Cross multiply
    718.02x = 990.81 × 399
  4. Step 4: Simplify right side
    718.02x = 395,333.19
  5. Step 5: Solve for x
    x = 395,333.19/718.02
  6. Step 6: Final answer
    x = 550.59

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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.