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Finding the Fourth Proportional to 71.91, 99.28 and 51.21

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Solution

The fourth proportional to 71.91, 99.28 and 51.21 is: 70.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.91 : 99.28 = 51.21 : x
  2. Step 2: Convert to fraction form
    71.91/99.28 = 51.21/x
  3. Step 3: Cross multiply
    71.91x = 99.28 × 51.21
  4. Step 4: Simplify right side
    71.91x = 5,084.13
  5. Step 5: Solve for x
    x = 5,084.13/71.91
  6. Step 6: Final answer
    x = 70.70

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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.