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Finding the Fourth Proportional to 21.45, 32.10 and 18.90

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Solution

The fourth proportional to 21.45, 32.10 and 18.90 is: 28.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.45 : 32.10 = 18.90 : x
  2. Step 2: Convert to fraction form
    21.45/32.10 = 18.90/x
  3. Step 3: Cross multiply
    21.45x = 32.10 × 18.90
  4. Step 4: Simplify right side
    21.45x = 606.69
  5. Step 5: Solve for x
    x = 606.69/21.45
  6. Step 6: Final answer
    x = 28.28

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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.