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Finding the Fourth Proportional to 39.99, 55.23 and 30.78

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Solution

The fourth proportional to 39.99, 55.23 and 30.78 is: 42.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.99 : 55.23 = 30.78 : x
  2. Step 2: Convert to fraction form
    39.99/55.23 = 30.78/x
  3. Step 3: Cross multiply
    39.99x = 55.23 × 30.78
  4. Step 4: Simplify right side
    39.99x = 1,699.98
  5. Step 5: Solve for x
    x = 1,699.98/39.99
  6. Step 6: Final answer
    x = 42.51

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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.