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Finding the Fourth Proportional to 13.85, 20.75 and 9.78

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Solution

The fourth proportional to 13.85, 20.75 and 9.78 is: 14.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.85 : 20.75 = 9.78 : x
  2. Step 2: Convert to fraction form
    13.85/20.75 = 9.78/x
  3. Step 3: Cross multiply
    13.85x = 20.75 × 9.78
  4. Step 4: Simplify right side
    13.85x = 202.89
  5. Step 5: Solve for x
    x = 202.89/13.85
  6. Step 6: Final answer
    x = 14.65

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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.