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Finding the Fourth Proportional to 1,321.32, 1,981.66 and 409.32

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Solution

The fourth proportional to 1,321.32, 1,981.66 and 409.32 is: 613.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.32 : 1,981.66 = 409.32 : x
  2. Step 2: Convert to fraction form
    1,321.32/1,981.66 = 409.32/x
  3. Step 3: Cross multiply
    1,321.32x = 1,981.66 × 409.32
  4. Step 4: Simplify right side
    1,321.32x = 811,133.07
  5. Step 5: Solve for x
    x = 811,133.07/1,321.32
  6. Step 6: Final answer
    x = 613.88

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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.