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Finding the Fourth Proportional to 258.45, 387.35 and 121.20

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Solution

The fourth proportional to 258.45, 387.35 and 121.20 is: 181.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.45 : 387.35 = 121.20 : x
  2. Step 2: Convert to fraction form
    258.45/387.35 = 121.20/x
  3. Step 3: Cross multiply
    258.45x = 387.35 × 121.20
  4. Step 4: Simplify right side
    258.45x = 46,946.40
  5. Step 5: Solve for x
    x = 46,946.40/258.45
  6. Step 6: Final answer
    x = 181.64

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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.