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Finding the Fourth Proportional to 128.45, 176.86 and 103.95

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Solution

The fourth proportional to 128.45, 176.86 and 103.95 is: 143.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.45 : 176.86 = 103.95 : x
  2. Step 2: Convert to fraction form
    128.45/176.86 = 103.95/x
  3. Step 3: Cross multiply
    128.45x = 176.86 × 103.95
  4. Step 4: Simplify right side
    128.45x = 18,384.60
  5. Step 5: Solve for x
    x = 18,384.60/128.45
  6. Step 6: Final answer
    x = 143.13

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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.