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Finding the Fourth Proportional to 128.66, 192.87 and 47.45

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Solution

The fourth proportional to 128.66, 192.87 and 47.45 is: 71.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.66 : 192.87 = 47.45 : x
  2. Step 2: Convert to fraction form
    128.66/192.87 = 47.45/x
  3. Step 3: Cross multiply
    128.66x = 192.87 × 47.45
  4. Step 4: Simplify right side
    128.66x = 9,151.68
  5. Step 5: Solve for x
    x = 9,151.68/128.66
  6. Step 6: Final answer
    x = 71.13

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.