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Finding the Fourth Proportional to 920.40, 1,378.65 and 724.47

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Solution

The fourth proportional to 920.40, 1,378.65 and 724.47 is: 1,085.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.40 : 1,378.65 = 724.47 : x
  2. Step 2: Convert to fraction form
    920.40/1,378.65 = 724.47/x
  3. Step 3: Cross multiply
    920.40x = 1,378.65 × 724.47
  4. Step 4: Simplify right side
    920.40x = 998,790.57
  5. Step 5: Solve for x
    x = 998,790.57/920.40
  6. Step 6: Final answer
    x = 1,085.17

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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.