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Finding the Fourth Proportional to 257.15, 385.21 and 120

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Solution

The fourth proportional to 257.15, 385.21 and 120 is: 179.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.15 : 385.21 = 120 : x
  2. Step 2: Convert to fraction form
    257.15/385.21 = 120/x
  3. Step 3: Cross multiply
    257.15x = 385.21 × 120
  4. Step 4: Simplify right side
    257.15x = 46,225.20
  5. Step 5: Solve for x
    x = 46,225.20/257.15
  6. Step 6: Final answer
    x = 179.76

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.