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Finding the Fourth Proportional to 57.12, 85.28 and 39.84

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Solution

The fourth proportional to 57.12, 85.28 and 39.84 is: 59.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.12 : 85.28 = 39.84 : x
  2. Step 2: Convert to fraction form
    57.12/85.28 = 39.84/x
  3. Step 3: Cross multiply
    57.12x = 85.28 × 39.84
  4. Step 4: Simplify right side
    57.12x = 3,397.36
  5. Step 5: Solve for x
    x = 3,397.36/57.12
  6. Step 6: Final answer
    x = 59.48

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.