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Finding the Fourth Proportional to 21.90, 30.15 and 17.28

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Solution

The fourth proportional to 21.90, 30.15 and 17.28 is: 23.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.90 : 30.15 = 17.28 : x
  2. Step 2: Convert to fraction form
    21.90/30.15 = 17.28/x
  3. Step 3: Cross multiply
    21.90x = 30.15 × 17.28
  4. Step 4: Simplify right side
    21.90x = 520.84
  5. Step 5: Solve for x
    x = 520.84/21.90
  6. Step 6: Final answer
    x = 23.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.