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Finding the Fourth Proportional to 21.07, 31.55 and 14.21

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Solution

The fourth proportional to 21.07, 31.55 and 14.21 is: 21.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.07 : 31.55 = 14.21 : x
  2. Step 2: Convert to fraction form
    21.07/31.55 = 14.21/x
  3. Step 3: Cross multiply
    21.07x = 31.55 × 14.21
  4. Step 4: Simplify right side
    21.07x = 448.45
  5. Step 5: Solve for x
    x = 448.45/21.07
  6. Step 6: Final answer
    x = 21.28

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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.