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Finding the Fourth Proportional to 9.78, 13.47 and 7.72

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Solution

The fourth proportional to 9.78, 13.47 and 7.72 is: 10.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.78 : 13.47 = 7.72 : x
  2. Step 2: Convert to fraction form
    9.78/13.47 = 7.72/x
  3. Step 3: Cross multiply
    9.78x = 13.47 × 7.72
  4. Step 4: Simplify right side
    9.78x = 103.99
  5. Step 5: Solve for x
    x = 103.99/9.78
  6. Step 6: Final answer
    x = 10.63

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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.