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Finding the Fourth Proportional to 785.80, 1,178.70 and 728.20

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Solution

The fourth proportional to 785.80, 1,178.70 and 728.20 is: 1,092.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.80 : 1,178.70 = 728.20 : x
  2. Step 2: Convert to fraction form
    785.80/1,178.70 = 728.20/x
  3. Step 3: Cross multiply
    785.80x = 1,178.70 × 728.20
  4. Step 4: Simplify right side
    785.80x = 858,329.34
  5. Step 5: Solve for x
    x = 858,329.34/785.80
  6. Step 6: Final answer
    x = 1,092.30

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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.