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Finding the Fourth Proportional to 73.12, 100.80 and 72.40

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Solution

The fourth proportional to 73.12, 100.80 and 72.40 is: 99.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    73.12 : 100.80 = 72.40 : x
  2. Step 2: Convert to fraction form
    73.12/100.80 = 72.40/x
  3. Step 3: Cross multiply
    73.12x = 100.80 × 72.40
  4. Step 4: Simplify right side
    73.12x = 7,297.92
  5. Step 5: Solve for x
    x = 7,297.92/73.12
  6. Step 6: Final answer
    x = 99.81

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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.