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Finding the Fourth Proportional to 258.93, 388.30 and 85.57

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Solution

The fourth proportional to 258.93, 388.30 and 85.57 is: 128.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.93 : 388.30 = 85.57 : x
  2. Step 2: Convert to fraction form
    258.93/388.30 = 85.57/x
  3. Step 3: Cross multiply
    258.93x = 388.30 × 85.57
  4. Step 4: Simplify right side
    258.93x = 33,225.10
  5. Step 5: Solve for x
    x = 33,225.10/258.93
  6. Step 6: Final answer
    x = 128.32

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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.