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Finding the Fourth Proportional to 40.42, 55.78 and 30.72

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Solution

The fourth proportional to 40.42, 55.78 and 30.72 is: 42.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    40.42 : 55.78 = 30.72 : x
  2. Step 2: Convert to fraction form
    40.42/55.78 = 30.72/x
  3. Step 3: Cross multiply
    40.42x = 55.78 × 30.72
  4. Step 4: Simplify right side
    40.42x = 1,713.56
  5. Step 5: Solve for x
    x = 1,713.56/40.42
  6. Step 6: Final answer
    x = 42.39

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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.