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Finding the Fourth Proportional to 655.86, 905.21 and 390.18

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Solution

The fourth proportional to 655.86, 905.21 and 390.18 is: 538.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    655.86 : 905.21 = 390.18 : x
  2. Step 2: Convert to fraction form
    655.86/905.21 = 390.18/x
  3. Step 3: Cross multiply
    655.86x = 905.21 × 390.18
  4. Step 4: Simplify right side
    655.86x = 353,194.84
  5. Step 5: Solve for x
    x = 353,194.84/655.86
  6. Step 6: Final answer
    x = 538.52

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.