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Finding the Fourth Proportional to 643.50, 965.28 and 258.78

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Solution

The fourth proportional to 643.50, 965.28 and 258.78 is: 388.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.50 : 965.28 = 258.78 : x
  2. Step 2: Convert to fraction form
    643.50/965.28 = 258.78/x
  3. Step 3: Cross multiply
    643.50x = 965.28 × 258.78
  4. Step 4: Simplify right side
    643.50x = 249,795.16
  5. Step 5: Solve for x
    x = 249,795.16/643.50
  6. Step 6: Final answer
    x = 388.18

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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.