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Finding the Fourth Proportional to 51.78, 71.45 and 31.07

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Solution

The fourth proportional to 51.78, 71.45 and 31.07 is: 42.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.78 : 71.45 = 31.07 : x
  2. Step 2: Convert to fraction form
    51.78/71.45 = 31.07/x
  3. Step 3: Cross multiply
    51.78x = 71.45 × 31.07
  4. Step 4: Simplify right side
    51.78x = 2,219.44
  5. Step 5: Solve for x
    x = 2,219.44/51.78
  6. Step 6: Final answer
    x = 42.86

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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.