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Finding the Fourth Proportional to 1,221.75, 1,685.61 and 724.55

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Solution

The fourth proportional to 1,221.75, 1,685.61 and 724.55 is: 999.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.75 : 1,685.61 = 724.55 : x
  2. Step 2: Convert to fraction form
    1,221.75/1,685.61 = 724.55/x
  3. Step 3: Cross multiply
    1,221.75x = 1,685.61 × 724.55
  4. Step 4: Simplify right side
    1,221.75x = 1,221,300.30
  5. Step 5: Solve for x
    x = 1,221,300.30/1,221.75
  6. Step 6: Final answer
    x = 999.63

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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.