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Finding the Fourth Proportional to 42.75, 64.16 and 18.71

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Solution

The fourth proportional to 42.75, 64.16 and 18.71 is: 28.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.75 : 64.16 = 18.71 : x
  2. Step 2: Convert to fraction form
    42.75/64.16 = 18.71/x
  3. Step 3: Cross multiply
    42.75x = 64.16 × 18.71
  4. Step 4: Simplify right side
    42.75x = 1,200.02
  5. Step 5: Solve for x
    x = 1,200.02/42.75
  6. Step 6: Final answer
    x = 28.07

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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.