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Finding the Fourth Proportional to 31.51, 47.21 and 18.64

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Solution

The fourth proportional to 31.51, 47.21 and 18.64 is: 27.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.51 : 47.21 = 18.64 : x
  2. Step 2: Convert to fraction form
    31.51/47.21 = 18.64/x
  3. Step 3: Cross multiply
    31.51x = 47.21 × 18.64
  4. Step 4: Simplify right side
    31.51x = 879.78
  5. Step 5: Solve for x
    x = 879.78/31.51
  6. Step 6: Final answer
    x = 27.92

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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.