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Finding the Fourth Proportional to 72.18, 99.61 and 39.43

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Solution

The fourth proportional to 72.18, 99.61 and 39.43 is: 54.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.18 : 99.61 = 39.43 : x
  2. Step 2: Convert to fraction form
    72.18/99.61 = 39.43/x
  3. Step 3: Cross multiply
    72.18x = 99.61 × 39.43
  4. Step 4: Simplify right side
    72.18x = 3,927.39
  5. Step 5: Solve for x
    x = 3,927.39/72.18
  6. Step 6: Final answer
    x = 54.41

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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.