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Finding the Fourth Proportional to 128.37, 176.95 and 86.91

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Solution

The fourth proportional to 128.37, 176.95 and 86.91 is: 119.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.37 : 176.95 = 86.91 : x
  2. Step 2: Convert to fraction form
    128.37/176.95 = 86.91/x
  3. Step 3: Cross multiply
    128.37x = 176.95 × 86.91
  4. Step 4: Simplify right side
    128.37x = 15,378.72
  5. Step 5: Solve for x
    x = 15,378.72/128.37
  6. Step 6: Final answer
    x = 119.80

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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.