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Finding the Fourth Proportional to 51.91, 77.86 and 21.08

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Solution

The fourth proportional to 51.91, 77.86 and 21.08 is: 31.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.91 : 77.86 = 21.08 : x
  2. Step 2: Convert to fraction form
    51.91/77.86 = 21.08/x
  3. Step 3: Cross multiply
    51.91x = 77.86 × 21.08
  4. Step 4: Simplify right side
    51.91x = 1,641.29
  5. Step 5: Solve for x
    x = 1,641.29/51.91
  6. Step 6: Final answer
    x = 31.62

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.