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Finding the Fourth Proportional to 1,221.11, 1,685.14 and 724

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Solution

The fourth proportional to 1,221.11, 1,685.14 and 724 is: 999.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.11 : 1,685.14 = 724 : x
  2. Step 2: Convert to fraction form
    1,221.11/1,685.14 = 724/x
  3. Step 3: Cross multiply
    1,221.11x = 1,685.14 × 724
  4. Step 4: Simplify right side
    1,221.11x = 1,220,041.36
  5. Step 5: Solve for x
    x = 1,220,041.36/1,221.11
  6. Step 6: Final answer
    x = 999.12

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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.