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Finding the Fourth Proportional to 390.86, 585.79 and 208.21

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Solution

The fourth proportional to 390.86, 585.79 and 208.21 is: 312.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.86 : 585.79 = 208.21 : x
  2. Step 2: Convert to fraction form
    390.86/585.79 = 208.21/x
  3. Step 3: Cross multiply
    390.86x = 585.79 × 208.21
  4. Step 4: Simplify right side
    390.86x = 121,967.34
  5. Step 5: Solve for x
    x = 121,967.34/390.86
  6. Step 6: Final answer
    x = 312.05

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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.