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Finding the Fourth Proportional to 7.15, 9.87 and 3.91

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Solution

The fourth proportional to 7.15, 9.87 and 3.91 is: 5.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.15 : 9.87 = 3.91 : x
  2. Step 2: Convert to fraction form
    7.15/9.87 = 3.91/x
  3. Step 3: Cross multiply
    7.15x = 9.87 × 3.91
  4. Step 4: Simplify right side
    7.15x = 38.61
  5. Step 5: Solve for x
    x = 38.61/7.15
  6. Step 6: Final answer
    x = 5.40

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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.