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Finding the Fourth Proportional to 86, 118.78 and 71.60

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Solution

The fourth proportional to 86, 118.78 and 71.60 is: 98.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    86 : 118.78 = 71.60 : x
  2. Step 2: Convert to fraction form
    86/118.78 = 71.60/x
  3. Step 3: Cross multiply
    86x = 118.78 × 71.60
  4. Step 4: Simplify right side
    86x = 8,504.65
  5. Step 5: Solve for x
    x = 8,504.65/86
  6. Step 6: Final answer
    x = 98.89

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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.