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Finding the Fourth Proportional to 408, 561.24 and 390.12

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Solution

The fourth proportional to 408, 561.24 and 390.12 is: 536.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    408 : 561.24 = 390.12 : x
  2. Step 2: Convert to fraction form
    408/561.24 = 390.12/x
  3. Step 3: Cross multiply
    408x = 561.24 × 390.12
  4. Step 4: Simplify right side
    408x = 218,950.95
  5. Step 5: Solve for x
    x = 218,950.95/408
  6. Step 6: Final answer
    x = 536.64

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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.