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Finding the Fourth Proportional to 985.91, 1,478.86 and 408.79

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Solution

The fourth proportional to 985.91, 1,478.86 and 408.79 is: 613.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.91 : 1,478.86 = 408.79 : x
  2. Step 2: Convert to fraction form
    985.91/1,478.86 = 408.79/x
  3. Step 3: Cross multiply
    985.91x = 1,478.86 × 408.79
  4. Step 4: Simplify right side
    985.91x = 604,533.74
  5. Step 5: Solve for x
    x = 604,533.74/985.91
  6. Step 6: Final answer
    x = 613.17

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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.