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Finding the Fourth Proportional to 390.79, 585.77 and 208.40

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Solution

The fourth proportional to 390.79, 585.77 and 208.40 is: 312.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.79 : 585.77 = 208.40 : x
  2. Step 2: Convert to fraction form
    390.79/585.77 = 208.40/x
  3. Step 3: Cross multiply
    390.79x = 585.77 × 208.40
  4. Step 4: Simplify right side
    390.79x = 122,074.47
  5. Step 5: Solve for x
    x = 122,074.47/390.79
  6. Step 6: Final answer
    x = 312.38

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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.