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Finding the Fourth Proportional to 820.39, 1,223.12 and 728.05

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Solution

The fourth proportional to 820.39, 1,223.12 and 728.05 is: 1,085.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.39 : 1,223.12 = 728.05 : x
  2. Step 2: Convert to fraction form
    820.39/1,223.12 = 728.05/x
  3. Step 3: Cross multiply
    820.39x = 1,223.12 × 728.05
  4. Step 4: Simplify right side
    820.39x = 890,492.52
  5. Step 5: Solve for x
    x = 890,492.52/820.39
  6. Step 6: Final answer
    x = 1,085.45

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.