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Finding the Fourth Proportional to 643.20, 963.90 and 258

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Solution

The fourth proportional to 643.20, 963.90 and 258 is: 386.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.20 : 963.90 = 258 : x
  2. Step 2: Convert to fraction form
    643.20/963.90 = 258/x
  3. Step 3: Cross multiply
    643.20x = 963.90 × 258
  4. Step 4: Simplify right side
    643.20x = 248,686.20
  5. Step 5: Solve for x
    x = 248,686.20/643.20
  6. Step 6: Final answer
    x = 386.64

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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.