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Finding the Fourth Proportional to 28.31, 42.40 and 21.07

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Solution

The fourth proportional to 28.31, 42.40 and 21.07 is: 31.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.31 : 42.40 = 21.07 : x
  2. Step 2: Convert to fraction form
    28.31/42.40 = 21.07/x
  3. Step 3: Cross multiply
    28.31x = 42.40 × 21.07
  4. Step 4: Simplify right side
    28.31x = 893.37
  5. Step 5: Solve for x
    x = 893.37/28.31
  6. Step 6: Final answer
    x = 31.56

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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.