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Finding the Fourth Proportional to 258.64, 388.09 and 128.66

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Solution

The fourth proportional to 258.64, 388.09 and 128.66 is: 193.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.64 : 388.09 = 128.66 : x
  2. Step 2: Convert to fraction form
    258.64/388.09 = 128.66/x
  3. Step 3: Cross multiply
    258.64x = 388.09 × 128.66
  4. Step 4: Simplify right side
    258.64x = 49,931.66
  5. Step 5: Solve for x
    x = 49,931.66/258.64
  6. Step 6: Final answer
    x = 193.05

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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.