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Finding the Fourth Proportional to 72.21, 99.65 and 39.47

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Solution

The fourth proportional to 72.21, 99.65 and 39.47 is: 54.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.21 : 99.65 = 39.47 : x
  2. Step 2: Convert to fraction form
    72.21/99.65 = 39.47/x
  3. Step 3: Cross multiply
    72.21x = 99.65 × 39.47
  4. Step 4: Simplify right side
    72.21x = 3,932.64
  5. Step 5: Solve for x
    x = 3,932.64/72.21
  6. Step 6: Final answer
    x = 54.46

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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.