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Finding the Fourth Proportional to 31.47, 43.42 and 21.13

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Solution

The fourth proportional to 31.47, 43.42 and 21.13 is: 29.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.47 : 43.42 = 21.13 : x
  2. Step 2: Convert to fraction form
    31.47/43.42 = 21.13/x
  3. Step 3: Cross multiply
    31.47x = 43.42 × 21.13
  4. Step 4: Simplify right side
    31.47x = 917.38
  5. Step 5: Solve for x
    x = 917.38/31.47
  6. Step 6: Final answer
    x = 29.15

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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.