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Finding the Fourth Proportional to 685.58, 1,021.50 and 612.90

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Solution

The fourth proportional to 685.58, 1,021.50 and 612.90 is: 913.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.58 : 1,021.50 = 612.90 : x
  2. Step 2: Convert to fraction form
    685.58/1,021.50 = 612.90/x
  3. Step 3: Cross multiply
    685.58x = 1,021.50 × 612.90
  4. Step 4: Simplify right side
    685.58x = 626,077.35
  5. Step 5: Solve for x
    x = 626,077.35/685.58
  6. Step 6: Final answer
    x = 913.21

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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.