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Finding the Fourth Proportional to 9.78, 13.47 and 8.42

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Solution

The fourth proportional to 9.78, 13.47 and 8.42 is: 11.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.78 : 13.47 = 8.42 : x
  2. Step 2: Convert to fraction form
    9.78/13.47 = 8.42/x
  3. Step 3: Cross multiply
    9.78x = 13.47 × 8.42
  4. Step 4: Simplify right side
    9.78x = 113.35
  5. Step 5: Solve for x
    x = 113.35/9.78
  6. Step 6: Final answer
    x = 11.59

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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.