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Finding the Fourth Proportional to 405.91, 559.95 and 390.19

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Solution

The fourth proportional to 405.91, 559.95 and 390.19 is: 538.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.91 : 559.95 = 390.19 : x
  2. Step 2: Convert to fraction form
    405.91/559.95 = 390.19/x
  3. Step 3: Cross multiply
    405.91x = 559.95 × 390.19
  4. Step 4: Simplify right side
    405.91x = 218,484.09
  5. Step 5: Solve for x
    x = 218,484.09/405.91
  6. Step 6: Final answer
    x = 538.26

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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.