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Finding the Fourth Proportional to 138.61, 191.30 and 86.16

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Solution

The fourth proportional to 138.61, 191.30 and 86.16 is: 118.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.61 : 191.30 = 86.16 : x
  2. Step 2: Convert to fraction form
    138.61/191.30 = 86.16/x
  3. Step 3: Cross multiply
    138.61x = 191.30 × 86.16
  4. Step 4: Simplify right side
    138.61x = 16,482.41
  5. Step 5: Solve for x
    x = 16,482.41/138.61
  6. Step 6: Final answer
    x = 118.91

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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.