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Finding the Fourth Proportional to 39.95, 55.16 and 30.72

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Solution

The fourth proportional to 39.95, 55.16 and 30.72 is: 42.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.95 : 55.16 = 30.72 : x
  2. Step 2: Convert to fraction form
    39.95/55.16 = 30.72/x
  3. Step 3: Cross multiply
    39.95x = 55.16 × 30.72
  4. Step 4: Simplify right side
    39.95x = 1,694.36
  5. Step 5: Solve for x
    x = 1,694.36/39.95
  6. Step 6: Final answer
    x = 42.42

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.