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Finding the Fourth Proportional to 86.20, 118.86 and 71.40

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Solution

The fourth proportional to 86.20, 118.86 and 71.40 is: 98.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.20 : 118.86 = 71.40 : x
  2. Step 2: Convert to fraction form
    86.20/118.86 = 71.40/x
  3. Step 3: Cross multiply
    86.20x = 118.86 × 71.40
  4. Step 4: Simplify right side
    86.20x = 8,486.60
  5. Step 5: Solve for x
    x = 8,486.60/86.20
  6. Step 6: Final answer
    x = 98.45

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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.