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Finding the Fourth Proportional to 12.40, 18.57 and 7.90

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Solution

The fourth proportional to 12.40, 18.57 and 7.90 is: 11.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.40 : 18.57 = 7.90 : x
  2. Step 2: Convert to fraction form
    12.40/18.57 = 7.90/x
  3. Step 3: Cross multiply
    12.40x = 18.57 × 7.90
  4. Step 4: Simplify right side
    12.40x = 146.61
  5. Step 5: Solve for x
    x = 146.61/12.40
  6. Step 6: Final answer
    x = 11.83

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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.