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Finding the Fourth Proportional to 258.19, 387.28 and 65.81

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Solution

The fourth proportional to 258.19, 387.28 and 65.81 is: 98.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.19 : 387.28 = 65.81 : x
  2. Step 2: Convert to fraction form
    258.19/387.28 = 65.81/x
  3. Step 3: Cross multiply
    258.19x = 387.28 × 65.81
  4. Step 4: Simplify right side
    258.19x = 25,487.95
  5. Step 5: Solve for x
    x = 25,487.95/258.19
  6. Step 6: Final answer
    x = 98.72

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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.