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Finding the Fourth Proportional to 1,221.42, 1,685.94 and 723.90

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Solution

The fourth proportional to 1,221.42, 1,685.94 and 723.90 is: 999.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.42 : 1,685.94 = 723.90 : x
  2. Step 2: Convert to fraction form
    1,221.42/1,685.94 = 723.90/x
  3. Step 3: Cross multiply
    1,221.42x = 1,685.94 × 723.90
  4. Step 4: Simplify right side
    1,221.42x = 1,220,451.97
  5. Step 5: Solve for x
    x = 1,220,451.97/1,221.42
  6. Step 6: Final answer
    x = 999.21

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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.