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Finding the Fourth Proportional to 202.19, 278.90 and 128.61

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Solution

The fourth proportional to 202.19, 278.90 and 128.61 is: 177.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    202.19 : 278.90 = 128.61 : x
  2. Step 2: Convert to fraction form
    202.19/278.90 = 128.61/x
  3. Step 3: Cross multiply
    202.19x = 278.90 × 128.61
  4. Step 4: Simplify right side
    202.19x = 35,868.12
  5. Step 5: Solve for x
    x = 35,868.12/202.19
  6. Step 6: Final answer
    x = 177.40

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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.