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Finding the Fourth Proportional to 985.72, 1,478.88 and 408.64

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Solution

The fourth proportional to 985.72, 1,478.88 and 408.64 is: 613.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.72 : 1,478.88 = 408.64 : x
  2. Step 2: Convert to fraction form
    985.72/1,478.88 = 408.64/x
  3. Step 3: Cross multiply
    985.72x = 1,478.88 × 408.64
  4. Step 4: Simplify right side
    985.72x = 604,329.52
  5. Step 5: Solve for x
    x = 604,329.52/985.72
  6. Step 6: Final answer
    x = 613.08

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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.