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Finding the Fourth Proportional to 80.72, 111.40 and 51.20

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Solution

The fourth proportional to 80.72, 111.40 and 51.20 is: 70.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 111.40 = 51.20 : x
  2. Step 2: Convert to fraction form
    80.72/111.40 = 51.20/x
  3. Step 3: Cross multiply
    80.72x = 111.40 × 51.20
  4. Step 4: Simplify right side
    80.72x = 5,703.68
  5. Step 5: Solve for x
    x = 5,703.68/80.72
  6. Step 6: Final answer
    x = 70.66

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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.