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Finding the Fourth Proportional to 1,409.56, 2,115.30 and 640.60

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Solution

The fourth proportional to 1,409.56, 2,115.30 and 640.60 is: 961.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,409.56 : 2,115.30 = 640.60 : x
  2. Step 2: Convert to fraction form
    1,409.56/2,115.30 = 640.60/x
  3. Step 3: Cross multiply
    1,409.56x = 2,115.30 × 640.60
  4. Step 4: Simplify right side
    1,409.56x = 1,355,061.18
  5. Step 5: Solve for x
    x = 1,355,061.18/1,409.56
  6. Step 6: Final answer
    x = 961.34

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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.