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Finding the Fourth Proportional to 728.50, 1,005.69 and 685.30

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Solution

The fourth proportional to 728.50, 1,005.69 and 685.30 is: 946.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.50 : 1,005.69 = 685.30 : x
  2. Step 2: Convert to fraction form
    728.50/1,005.69 = 685.30/x
  3. Step 3: Cross multiply
    728.50x = 1,005.69 × 685.30
  4. Step 4: Simplify right side
    728.50x = 689,199.36
  5. Step 5: Solve for x
    x = 689,199.36/728.50
  6. Step 6: Final answer
    x = 946.05

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.