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Finding the Fourth Proportional to 661.04, 912.12 and 399

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Solution

The fourth proportional to 661.04, 912.12 and 399 is: 550.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.04 : 912.12 = 399 : x
  2. Step 2: Convert to fraction form
    661.04/912.12 = 399/x
  3. Step 3: Cross multiply
    661.04x = 912.12 × 399
  4. Step 4: Simplify right side
    661.04x = 363,935.88
  5. Step 5: Solve for x
    x = 363,935.88/661.04
  6. Step 6: Final answer
    x = 550.55

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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.