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Finding the Fourth Proportional to 258.35, 387 and 121.21

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Solution

The fourth proportional to 258.35, 387 and 121.21 is: 181.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.35 : 387 = 121.21 : x
  2. Step 2: Convert to fraction form
    258.35/387 = 121.21/x
  3. Step 3: Cross multiply
    258.35x = 387 × 121.21
  4. Step 4: Simplify right side
    258.35x = 46,907.30
  5. Step 5: Solve for x
    x = 46,907.30/258.35
  6. Step 6: Final answer
    x = 181.57

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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.