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Finding the Fourth Proportional to 1,378.91, 2,069.74 and 649

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Solution

The fourth proportional to 1,378.91, 2,069.74 and 649 is: 974.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.91 : 2,069.74 = 649 : x
  2. Step 2: Convert to fraction form
    1,378.91/2,069.74 = 649/x
  3. Step 3: Cross multiply
    1,378.91x = 2,069.74 × 649
  4. Step 4: Simplify right side
    1,378.91x = 1,343,258.02
  5. Step 5: Solve for x
    x = 1,343,258.02/1,378.91
  6. Step 6: Final answer
    x = 974.14

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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.