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Finding the Fourth Proportional to 1,420.91, 2,129.64 and 640.71

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Solution

The fourth proportional to 1,420.91, 2,129.64 and 640.71 is: 960.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.91 : 2,129.64 = 640.71 : x
  2. Step 2: Convert to fraction form
    1,420.91/2,129.64 = 640.71/x
  3. Step 3: Cross multiply
    1,420.91x = 2,129.64 × 640.71
  4. Step 4: Simplify right side
    1,420.91x = 1,364,482.85
  5. Step 5: Solve for x
    x = 1,364,482.85/1,420.91
  6. Step 6: Final answer
    x = 960.29

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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.