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Finding the Fourth Proportional to 72.20, 99.66 and 53.78

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Solution

The fourth proportional to 72.20, 99.66 and 53.78 is: 74.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.20 : 99.66 = 53.78 : x
  2. Step 2: Convert to fraction form
    72.20/99.66 = 53.78/x
  3. Step 3: Cross multiply
    72.20x = 99.66 × 53.78
  4. Step 4: Simplify right side
    72.20x = 5,359.71
  5. Step 5: Solve for x
    x = 5,359.71/72.20
  6. Step 6: Final answer
    x = 74.23

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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.