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Finding the Fourth Proportional to 643.40, 965.38 and 318.58

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Solution

The fourth proportional to 643.40, 965.38 and 318.58 is: 478.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.40 : 965.38 = 318.58 : x
  2. Step 2: Convert to fraction form
    643.40/965.38 = 318.58/x
  3. Step 3: Cross multiply
    643.40x = 965.38 × 318.58
  4. Step 4: Simplify right side
    643.40x = 307,550.76
  5. Step 5: Solve for x
    x = 307,550.76/643.40
  6. Step 6: Final answer
    x = 478.01

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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.