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Finding the Fourth Proportional to 1,217.61, 1,679.91 and 720.42

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Solution

The fourth proportional to 1,217.61, 1,679.91 and 720.42 is: 993.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.61 : 1,679.91 = 720.42 : x
  2. Step 2: Convert to fraction form
    1,217.61/1,679.91 = 720.42/x
  3. Step 3: Cross multiply
    1,217.61x = 1,679.91 × 720.42
  4. Step 4: Simplify right side
    1,217.61x = 1,210,240.76
  5. Step 5: Solve for x
    x = 1,210,240.76/1,217.61
  6. Step 6: Final answer
    x = 993.95

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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.