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Finding the Fourth Proportional to 985.64, 1,478.39 and 255.20

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Solution

The fourth proportional to 985.64, 1,478.39 and 255.20 is: 382.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.64 : 1,478.39 = 255.20 : x
  2. Step 2: Convert to fraction form
    985.64/1,478.39 = 255.20/x
  3. Step 3: Cross multiply
    985.64x = 1,478.39 × 255.20
  4. Step 4: Simplify right side
    985.64x = 377,278.37
  5. Step 5: Solve for x
    x = 377,278.37/985.64
  6. Step 6: Final answer
    x = 382.77

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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.