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Finding the Fourth Proportional to 815.39, 1,223.72 and 328.78

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Solution

The fourth proportional to 815.39, 1,223.72 and 328.78 is: 493.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.39 : 1,223.72 = 328.78 : x
  2. Step 2: Convert to fraction form
    815.39/1,223.72 = 328.78/x
  3. Step 3: Cross multiply
    815.39x = 1,223.72 × 328.78
  4. Step 4: Simplify right side
    815.39x = 402,334.66
  5. Step 5: Solve for x
    x = 402,334.66/815.39
  6. Step 6: Final answer
    x = 493.43

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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.