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Finding the Fourth Proportional to 39.90, 55.08 and 30.18

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Solution

The fourth proportional to 39.90, 55.08 and 30.18 is: 41.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.90 : 55.08 = 30.18 : x
  2. Step 2: Convert to fraction form
    39.90/55.08 = 30.18/x
  3. Step 3: Cross multiply
    39.90x = 55.08 × 30.18
  4. Step 4: Simplify right side
    39.90x = 1,662.31
  5. Step 5: Solve for x
    x = 1,662.31/39.90
  6. Step 6: Final answer
    x = 41.66

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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.