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Finding the Fourth Proportional to 1,217.39, 1,679.22 and 720

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Solution

The fourth proportional to 1,217.39, 1,679.22 and 720 is: 993.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.39 : 1,679.22 = 720 : x
  2. Step 2: Convert to fraction form
    1,217.39/1,679.22 = 720/x
  3. Step 3: Cross multiply
    1,217.39x = 1,679.22 × 720
  4. Step 4: Simplify right side
    1,217.39x = 1,209,038.40
  5. Step 5: Solve for x
    x = 1,209,038.40/1,217.39
  6. Step 6: Final answer
    x = 993.14

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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.