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Finding the Fourth Proportional to 985.51, 1,478.81 and 408.25

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Solution

The fourth proportional to 985.51, 1,478.81 and 408.25 is: 612.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.51 : 1,478.81 = 408.25 : x
  2. Step 2: Convert to fraction form
    985.51/1,478.81 = 408.25/x
  3. Step 3: Cross multiply
    985.51x = 1,478.81 × 408.25
  4. Step 4: Simplify right side
    985.51x = 603,724.18
  5. Step 5: Solve for x
    x = 603,724.18/985.51
  6. Step 6: Final answer
    x = 612.60

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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.