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Finding the Fourth Proportional to 1,320, 1,980.32 and 408

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Solution

The fourth proportional to 1,320, 1,980.32 and 408 is: 612.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320 : 1,980.32 = 408 : x
  2. Step 2: Convert to fraction form
    1,320/1,980.32 = 408/x
  3. Step 3: Cross multiply
    1,320x = 1,980.32 × 408
  4. Step 4: Simplify right side
    1,320x = 807,970.56
  5. Step 5: Solve for x
    x = 807,970.56/1,320
  6. Step 6: Final answer
    x = 612.10

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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.