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Finding the Fourth Proportional to 405.68, 611.55 and 389.21

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Solution

The fourth proportional to 405.68, 611.55 and 389.21 is: 586.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.68 : 611.55 = 389.21 : x
  2. Step 2: Convert to fraction form
    405.68/611.55 = 389.21/x
  3. Step 3: Cross multiply
    405.68x = 611.55 × 389.21
  4. Step 4: Simplify right side
    405.68x = 238,018.32
  5. Step 5: Solve for x
    x = 238,018.32/405.68
  6. Step 6: Final answer
    x = 586.72

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.