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Finding the Fourth Proportional to 10, 15 and 7.86

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Solution

The fourth proportional to 10, 15 and 7.86 is: 11.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    10 : 15 = 7.86 : x
  2. Step 2: Convert to fraction form
    10/15 = 7.86/x
  3. Step 3: Cross multiply
    10x = 15 × 7.86
  4. Step 4: Simplify right side
    10x = 117.90
  5. Step 5: Solve for x
    x = 117.90/10
  6. Step 6: Final answer
    x = 11.79

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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.