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Finding the Fourth Proportional to 71.91, 99.20 and 42.79

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Solution

The fourth proportional to 71.91, 99.20 and 42.79 is: 59.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.91 : 99.20 = 42.79 : x
  2. Step 2: Convert to fraction form
    71.91/99.20 = 42.79/x
  3. Step 3: Cross multiply
    71.91x = 99.20 × 42.79
  4. Step 4: Simplify right side
    71.91x = 4,244.77
  5. Step 5: Solve for x
    x = 4,244.77/71.91
  6. Step 6: Final answer
    x = 59.03

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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.