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Finding the Fourth Proportional to 28.21, 42.31 and 21.45

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Solution

The fourth proportional to 28.21, 42.31 and 21.45 is: 32.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.21 : 42.31 = 21.45 : x
  2. Step 2: Convert to fraction form
    28.21/42.31 = 21.45/x
  3. Step 3: Cross multiply
    28.21x = 42.31 × 21.45
  4. Step 4: Simplify right side
    28.21x = 907.38
  5. Step 5: Solve for x
    x = 907.38/28.21
  6. Step 6: Final answer
    x = 32.17

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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.