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Finding the Fourth Proportional to 74.78, 112.17 and 31.45

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Solution

The fourth proportional to 74.78, 112.17 and 31.45 is: 47.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.78 : 112.17 = 31.45 : x
  2. Step 2: Convert to fraction form
    74.78/112.17 = 31.45/x
  3. Step 3: Cross multiply
    74.78x = 112.17 × 31.45
  4. Step 4: Simplify right side
    74.78x = 3,527.62
  5. Step 5: Solve for x
    x = 3,527.62/74.78
  6. Step 6: Final answer
    x = 47.17

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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.