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Finding the Fourth Proportional to 678.74, 1,017.37 and 485.78

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Solution

The fourth proportional to 678.74, 1,017.37 and 485.78 is: 728.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.74 : 1,017.37 = 485.78 : x
  2. Step 2: Convert to fraction form
    678.74/1,017.37 = 485.78/x
  3. Step 3: Cross multiply
    678.74x = 1,017.37 × 485.78
  4. Step 4: Simplify right side
    678.74x = 494,218.00
  5. Step 5: Solve for x
    x = 494,218.00/678.74
  6. Step 6: Final answer
    x = 728.14

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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.