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Finding the Fourth Proportional to 87.99, 121.47 and 61.80

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Solution

The fourth proportional to 87.99, 121.47 and 61.80 is: 85.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.99 : 121.47 = 61.80 : x
  2. Step 2: Convert to fraction form
    87.99/121.47 = 61.80/x
  3. Step 3: Cross multiply
    87.99x = 121.47 × 61.80
  4. Step 4: Simplify right side
    87.99x = 7,506.85
  5. Step 5: Solve for x
    x = 7,506.85/87.99
  6. Step 6: Final answer
    x = 85.31

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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.