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Finding the Fourth Proportional to 1,920.54, 2,880 and 687.72

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Solution

The fourth proportional to 1,920.54, 2,880 and 687.72 is: 1,031.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,920.54 : 2,880 = 687.72 : x
  2. Step 2: Convert to fraction form
    1,920.54/2,880 = 687.72/x
  3. Step 3: Cross multiply
    1,920.54x = 2,880 × 687.72
  4. Step 4: Simplify right side
    1,920.54x = 1,980,633.60
  5. Step 5: Solve for x
    x = 1,980,633.60/1,920.54
  6. Step 6: Final answer
    x = 1,031.29

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.