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Finding the Fourth Proportional to 257.21, 385.70 and 74.56

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Solution

The fourth proportional to 257.21, 385.70 and 74.56 is: 111.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.21 : 385.70 = 74.56 : x
  2. Step 2: Convert to fraction form
    257.21/385.70 = 74.56/x
  3. Step 3: Cross multiply
    257.21x = 385.70 × 74.56
  4. Step 4: Simplify right side
    257.21x = 28,756.45
  5. Step 5: Solve for x
    x = 28,756.45/257.21
  6. Step 6: Final answer
    x = 111.80

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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.