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Finding the Fourth Proportional to 143.20, 214.80 and 128.80

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Solution

The fourth proportional to 143.20, 214.80 and 128.80 is: 193.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.20 : 214.80 = 128.80 : x
  2. Step 2: Convert to fraction form
    143.20/214.80 = 128.80/x
  3. Step 3: Cross multiply
    143.20x = 214.80 × 128.80
  4. Step 4: Simplify right side
    143.20x = 27,666.24
  5. Step 5: Solve for x
    x = 27,666.24/143.20
  6. Step 6: Final answer
    x = 193.20

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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.