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Finding the Fourth Proportional to 42.79, 64.18 and 18.74

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Solution

The fourth proportional to 42.79, 64.18 and 18.74 is: 28.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.79 : 64.18 = 18.74 : x
  2. Step 2: Convert to fraction form
    42.79/64.18 = 18.74/x
  3. Step 3: Cross multiply
    42.79x = 64.18 × 18.74
  4. Step 4: Simplify right side
    42.79x = 1,202.73
  5. Step 5: Solve for x
    x = 1,202.73/42.79
  6. Step 6: Final answer
    x = 28.11

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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.