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Finding the Fourth Proportional to 21.42, 31.95 and 19.72

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Solution

The fourth proportional to 21.42, 31.95 and 19.72 is: 29.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.42 : 31.95 = 19.72 : x
  2. Step 2: Convert to fraction form
    21.42/31.95 = 19.72/x
  3. Step 3: Cross multiply
    21.42x = 31.95 × 19.72
  4. Step 4: Simplify right side
    21.42x = 629.97
  5. Step 5: Solve for x
    x = 629.97/21.42
  6. Step 6: Final answer
    x = 29.41

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.