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Finding the Fourth Proportional to 405.28, 558.30 and 390.88

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Solution

The fourth proportional to 405.28, 558.30 and 390.88 is: 538.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.28 : 558.30 = 390.88 : x
  2. Step 2: Convert to fraction form
    405.28/558.30 = 390.88/x
  3. Step 3: Cross multiply
    405.28x = 558.30 × 390.88
  4. Step 4: Simplify right side
    405.28x = 218,228.30
  5. Step 5: Solve for x
    x = 218,228.30/405.28
  6. Step 6: Final answer
    x = 538.46

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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.