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Finding the Fourth Proportional to 28.19, 42.08 and 21.42

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Solution

The fourth proportional to 28.19, 42.08 and 21.42 is: 31.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.19 : 42.08 = 21.42 : x
  2. Step 2: Convert to fraction form
    28.19/42.08 = 21.42/x
  3. Step 3: Cross multiply
    28.19x = 42.08 × 21.42
  4. Step 4: Simplify right side
    28.19x = 901.25
  5. Step 5: Solve for x
    x = 901.25/28.19
  6. Step 6: Final answer
    x = 31.98

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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.