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Finding the Fourth Proportional to 12.80, 19.21 and 7.40

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Solution

The fourth proportional to 12.80, 19.21 and 7.40 is: 11.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.80 : 19.21 = 7.40 : x
  2. Step 2: Convert to fraction form
    12.80/19.21 = 7.40/x
  3. Step 3: Cross multiply
    12.80x = 19.21 × 7.40
  4. Step 4: Simplify right side
    12.80x = 142.08
  5. Step 5: Solve for x
    x = 142.08/12.80
  6. Step 6: Final answer
    x = 11.10

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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.