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Finding the Fourth Proportional to 79.85, 109.95 and 71.75

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Solution

The fourth proportional to 79.85, 109.95 and 71.75 is: 98.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.85 : 109.95 = 71.75 : x
  2. Step 2: Convert to fraction form
    79.85/109.95 = 71.75/x
  3. Step 3: Cross multiply
    79.85x = 109.95 × 71.75
  4. Step 4: Simplify right side
    79.85x = 7,888.91
  5. Step 5: Solve for x
    x = 7,888.91/79.85
  6. Step 6: Final answer
    x = 98.80

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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.