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Finding the Fourth Proportional to 1,385.86, 2,078.78 and 398.70

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Solution

The fourth proportional to 1,385.86, 2,078.78 and 398.70 is: 598.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.86 : 2,078.78 = 398.70 : x
  2. Step 2: Convert to fraction form
    1,385.86/2,078.78 = 398.70/x
  3. Step 3: Cross multiply
    1,385.86x = 2,078.78 × 398.70
  4. Step 4: Simplify right side
    1,385.86x = 828,803.99
  5. Step 5: Solve for x
    x = 828,803.99/1,385.86
  6. Step 6: Final answer
    x = 598.04

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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.