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Finding the Fourth Proportional to 1,290, 1,934.84 and 640.20

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Solution

The fourth proportional to 1,290, 1,934.84 and 640.20 is: 960.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290 : 1,934.84 = 640.20 : x
  2. Step 2: Convert to fraction form
    1,290/1,934.84 = 640.20/x
  3. Step 3: Cross multiply
    1,290x = 1,934.84 × 640.20
  4. Step 4: Simplify right side
    1,290x = 1,238,684.57
  5. Step 5: Solve for x
    x = 1,238,684.57/1,290
  6. Step 6: Final answer
    x = 960.22

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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.