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Finding the Fourth Proportional to 1,290.79, 1,934.97 and 640.90

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Solution

The fourth proportional to 1,290.79, 1,934.97 and 640.90 is: 960.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.79 : 1,934.97 = 640.90 : x
  2. Step 2: Convert to fraction form
    1,290.79/1,934.97 = 640.90/x
  3. Step 3: Cross multiply
    1,290.79x = 1,934.97 × 640.90
  4. Step 4: Simplify right side
    1,290.79x = 1,240,122.27
  5. Step 5: Solve for x
    x = 1,240,122.27/1,290.79
  6. Step 6: Final answer
    x = 960.75

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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.