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Finding the Fourth Proportional to 72.20, 99.64 and 39.46

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Solution

The fourth proportional to 72.20, 99.64 and 39.46 is: 54.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.20 : 99.64 = 39.46 : x
  2. Step 2: Convert to fraction form
    72.20/99.64 = 39.46/x
  3. Step 3: Cross multiply
    72.20x = 99.64 × 39.46
  4. Step 4: Simplify right side
    72.20x = 3,931.32
  5. Step 5: Solve for x
    x = 3,931.32/72.20
  6. Step 6: Final answer
    x = 54.45

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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.