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Finding the Fourth Proportional to 31.78, 43.89 and 31.30

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Solution

The fourth proportional to 31.78, 43.89 and 31.30 is: 43.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.78 : 43.89 = 31.30 : x
  2. Step 2: Convert to fraction form
    31.78/43.89 = 31.30/x
  3. Step 3: Cross multiply
    31.78x = 43.89 × 31.30
  4. Step 4: Simplify right side
    31.78x = 1,373.76
  5. Step 5: Solve for x
    x = 1,373.76/31.78
  6. Step 6: Final answer
    x = 43.23

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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.