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Finding the Fourth Proportional to 7.91, 10.89 and 7.15

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Solution

The fourth proportional to 7.91, 10.89 and 7.15 is: 9.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.91 : 10.89 = 7.15 : x
  2. Step 2: Convert to fraction form
    7.91/10.89 = 7.15/x
  3. Step 3: Cross multiply
    7.91x = 10.89 × 7.15
  4. Step 4: Simplify right side
    7.91x = 77.86
  5. Step 5: Solve for x
    x = 77.86/7.91
  6. Step 6: Final answer
    x = 9.84

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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.